The User Profile Service failed the logon

SYMPTOMS

When you log on to a Windows 7-based or a Windows Vista-based computer by using a temporary profile, you receive the following error message:

The User Profile Service failed the logon. User profile cannot be loaded.

 

RESOLUTION

Occasionally, Windows might not read your user profile correctly, such as if your antivirus software is scanning your computer while you try to log on. Before you follow the methods here, try restarting your computer and logging on with your user account again to resolve the issue. If you restart your computer and it does not resolve this issue, use the following methods to resolve this issue.

Note You must be able to log on to an administrator account to fix your user profile or copy your data to a new account. Before you resolve the issue, log on to Windows by using another account that has administrative permissions, or restart in safe mode to log on with the built-in administrator account. For more information about how to start in safe mode, visit the following Microsoft website:

Method 1: Fix the user account profile

To fix the user account profile, follow these steps:

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

How to back up and restore the registry in Windows

1. Click Start, type regedit in the Search box, and then press ENTER.
2. In Registry Editor, locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
3. In the navigation pane, locate the folder that begins with S-1-5 (SID key) followed by a long number.
4. Click each S-1-5 folder, locate the ProfileImagePath entry in the details pane, and then double-click to make sure that this is the user account profile that has the error.
   
   
   
   
   • If you have two folders starting with S-1-5 followed by some long numbers and one of them ended with .bak, you have to rename the .bak folder. To do this, follow these steps:
     1. Right-click the folder without .bak, and then click Rename. Type .ba, and then press ENTER.
        
        
     2. Right-click the folder that is named .bak, and then click Rename. Remove .bak at the end of the folder name, and then press ENTER.
        
        
     3. Right-click the folder that is named .ba, and then click Rename. Change the .ba to .bak at the end of the folder name, and then press ENTER.
        
        
   • If you have only one folder starting with S-1-5 that is followed by long numbers and ends with .bak. Right-click the folder, and then click Rename. Remove .bak at the end of the folder name, and then press ENTER.
   • If you have two folders starting with S-1-5 followed by some long numbers and one of them ended with .bak, you have to rename the .bak folder. To do this, follow these steps:
     1. Right-click the folder without .bak, and then click Rename. Type .ba, and then press ENTER.
        
        
     2. Right-click the folder that is named .bak, and then click Rename. Remove .bak at the end of the folder name, and then press ENTER.
        
        
     3. Right-click the folder that is named .ba, and then click Rename. Change the .ba to .bak at the end of the folder name, and then press ENTER.
        
        
   • If you have only one folder starting with S-1-5 that is followed by long numbers and ends with .bak. Right-click the folder, and then click Rename. Remove .bak at the end of the folder name, and then press ENTER.
5. Double-click the folder without .bak in the details pane, double-click RefCount, type 0, and then click OK.
   
   
6. Click the folder without .bak, in the details pane, double-click State, type 0, and then click OK.
   
   
7. Close Registry Editor.
8. Restart the computer.
9. Log on again with your account.

 

Method 2: Log on to Windows and copy your data to a new account

Create a new account and copy the data from the old account to the new account. For information about how to do this, visit one of the following Microsoft websites: 

Windows 7

Windows Vista

Method 3: Delete the error SID and create a new profile

 To delete the error SID and create a new profile, follow these steps:

1. Delete the error SID.
   To have us fix this problem for you, go to the "Fix it for me" section. If you would rather fix it yourself, go to the "Let me fix it myself" section.
   
   

   Fix it for me

   To fix this problem automatically, click the Fix this problem link. Then click Run in the File Download dialog box, and follow the steps in this wizard.
   
   Fix this problem
   Microsoft Fix it 50446
   
   Notes
   • This wizard may be in English only, but the automatic fix also works for other language versions of Windows.
   • If you are not on the computer that has the problem, you can save the automatic fix to a flash drive or to a CD, and then you can run it on the computer that has the problem.
   
   

   Let me fix it myself
   

   Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
   How to back up and restore the registry in Windows
   
   To resolve this problem yourself, follow these steps:
   1. Delete the profile by using the Computer Properties dialog box. To do this, follow these steps:
      1. Click Start, right-click Computer, and then click Properties.
      2. Click Change settings.
         
         
         
      3. In the System Properties dialog box, click the Advanced tab.
         
         
         
      4. In the User Profiles area, click Settings.
      5. In the User Profiles dialog box, select the profile that you want to delete, click Delete, and then click OK.
   2. Click Start, type regedit in the Search box, and then press ENTER.
   3. Locate and then click the following registry subkey:
      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
   4. Right-click the SID that you want to remove, and then click Delete.
2. Log on to the computer and create a new profile.

Source: http://support.microsoft.com/kb/947215

USB 2.0 vs USB 3.0

With the growing hype surrounding USB 3.0, we thought it would be a nice idea to show the difference between USB 3.0 and its predecessor USB 2.0  in a easy to read, easy to understand format.
Below you will notice a chart detailing the main differences between USB 2.0 and USB 3.0 in addition to descriptions of exactly what is being compared.





Backward Compatible: Backward compatibility is whether the technology is compatible with previous platforms. Example: USB 3.0 is compatible with USB 2.0 and 1.1. This means that you can plug a USB 3.0 flash drive into a USB 2.0 port, but the transfer speeds will be limited by 2.0 specifications.
Maximum Transfer Rate: Exactly how fast can the connection transfer data? The higher the number, the greater the amount of files you can transfer per minute.
Bi-Directional Data Transfer: Bi-directional data transfer is new to USB 3.0 and allows a user to simultaneously upload and download files from a USB 3.0 device. USB 2.0 devices can only transfer files one way at any given moment.
Charging Power: Charging power refers to the amount of power that is transferred through a cable or port to charge a particular device. Devices that crave a lot of power such as an iPad benefit more from the increased power in USB 3.0 than 2.0. More power usually means faster charging rates.
Smart Charging: Smart Charging refers to if the USB protocol can sense if a device is plugged into the USB device or not. Standard USB 2.0 cannot detect when a device is plugged in, but will supply power to the port continuously. USB 3.0 on the other hand does have the protocol and will actually stop supplying power to a particular USB drive or port when not in use.
First Available: Refers to when devices like flash drives for this specification were first available to consumers.
There are more features that developers have created to make 3.0 an effective data transfer medium.  To help you further understand what sets SuperSpeed apart, it’s also important to know about the following USB 3.0 versus USB 2.0 differences:
A change of color. USB 3.0 takes a departure from USB 2.0’s black and gray cables.  Instead, cords and even ports are colored with a bright blue hue (as well as a more curled and swirled SuperSpeed logo imprinted on the connector).  These changes should help consumers better distinguish between the two standards.
Connectors and compatibility. Backward compatibility isn’t always clear cut.  A type A USB 3.0 plug with its thin yet broad structure is nearly identical to the 2.0 counterpart, which makes for a smooth, compatible connection between device and host in a 2.0 A port.  USB 2.0 A and B plugs will fit into their corresponding 3.0 ports.  However, Type B and Micro B USB 3.0 connectors are designed only for SuperSpeed devices and ports due to the nature of their shapes.  Type B USB 3.0 ports will however, accept 2.0 plugs.
Data hungry? USB 3.0 is better equipped at handling more data at a greater bandwidth than 2.0, providing double the throughput for devices like hard drives.  Where USB 2.0 was not able to handle certain Blu-ray players, video cameras and audio channels at optimum efficiency for the overall enjoyment of consumers, 3.0 is able to step up.
Making it easier to be green. While USB 3.0 uses multiplied charging power, the interface is actually more energy efficient than USB 2.0.  With asynchronous polling, USB 3.0 has the peripheral alert the host only when data needs to be transferred, therefore reducing power demands.  With USB 2.0, energy was wasted with continuous polling.  SuperSpeed also has the computer or devices reduce power when idle through link level power management.  The LPM feature first appeared in some but not all USB 2.0 devices because it was difficult to integrate.  However, it is a standard feature in USB 3.0.


Source: http://blog.premiumusb.com/2010/09/usb-2-0-vs-usb-3-0/