Reboot and login with safe mode (press f8 continuously and select safe mode)
2. Go in c:\windows\system32\ folder and delete (or rename) following file:
wgatray.exe, wgatray.exe,
Note: Dllcache is a hidden folder, to view hidden folders do the following, go to Start, Control Panel, Folder Options,
Select the view Tab and under the Hidden Files option, select Show hidden files and folders
Click on Start, Run and within the open dialog box type regedit and click OK.
* Within the Registry Editor navigate your self to
HKEY_Local_Machine\Software\Microsoft\WindowsNT\CurrentVersion\Winlogon\Notify\WGALOGON
* Right Click and Export the WGALOGON Folder (this should be saved onto your machine for backup purposes)
* After Exporting the folder, DELETE the WGALOGON folder
* After deleting close all applications and Restart your machine back to Normal Mode
Hope you can go out of the trouble.
Good luck!
Anubhav, November 2008