You receive a "The User Profile Service failed the logon” error message

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:
   322756 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 clickOK.
   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.

http://support.microsoft.com/kb/947215/en-us#fixit4me