I recently added Service Pack 3 to a Windows XP Professional pc. When the load was all done and I did a restart I came to an absolutely blank screen (not even a Taskbar)....after having entered my password. I found out in another answer here in EE that I should open the Windows Task Manager and do a File/New Task/Run explorer.exe. I tried that to no avail and, then noticed that there were two explorer.exe entries. I got rid of them both and, then, did another File/New Task/Run explorer.exe. This time everything came to the screen just fine. I tried several applications, looked at windows explorer, etc. and everything was ok. However, when I shut down and then started back up I came to the same blank screen. When I repeated the earlier process everything appeared ok. However, each time I reboot I have the same problem.