In XP you can delete/rename the c:documents and settings(username) and get the user to login and all will be well. If you do the same type of thing on a windows 7 pc delete/rename the c:users(username) and get the user to login your user will get the following message
*You have been logged on with a temporary profile* in the bottom right hand corner of the screen
If you wish to do it long hand then you will need to do the following:
  • Click Start, right-click Computer, and then click Properties.
  • Click Change settings.
  • In the System Properties dialog box, click the Advanced tab.
  • Under User Profiles, click Settings.
  • In the User Profiles dialog box, select the profile that you want to delete, click Delete, and then click OK.
  • Click Start, type regedit in the Start search box, and then press ENTER.
  • Locate and then expand the following registry subkey:
HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionProfileList
  • In the left pane, look for the folder name starting with S-1-5 (SID key) followed by a long number. 
  • Click each folder and locate ProfileImagePath from the right pane, double click to verify that this is the user account profile that has the error.
  • Right-click the SID that you want to remove, and then click Delete.
  • Restart the PC