An Idea
If there is something wrong with your explorer.exe file, u could get windows to replace it from the cd, now i expect there is a shorter way around what i am about to say but here goes
Click Start
Run then type %systemroot%\system32\Restore
(u need to have system and folder options enable to see the next file if u don't know how to do this post and i will explain)
Open Filelist.xml in notpad and add this line above
<REC>%sytemroot%\explorer.exe</REC>
<REC>%windir%\system.ini</REC>
Click Start
Run then type %systemroot%\system32\dllcache
Find explorer.exe in that folder and u should now be able to delete it.
Copy that file first incase it all goes horrbile wrong
Download resource hacker from
http://www.rpi.net.au/~ajohnson/resourcehacker/index.html
(does html work on this forum?)
Open resource hacker and open explorer.exe by browsing to the windows folder. Now change a string value say change where start is written on string 37 and 38 to Finish.
Now go control alt delete to bring task manger up go into the processes part displable explorer.exe.
Now open resource hacker by clicking
in the task manger on applications and click save when windows askes if u want to replace the dody copy click yes.
Well thats my long way of doing it i expect that someone will post a way of doing that in a couple of lines