Error-at start up win.xp (userinit.exe)

When I start Windows XP Home Edition, I get an error message saying that I have a file missing called "userinit.exe" and it says to insert disc. I just tried reinstalling Windows XP from my CD, but this did NOT correct the problem. In fact, Windows is starting even slower now. I have not redownloaded Windows XP Service Pack 2 yet. I tried to search for help on the Microsoft Web Site, and couldn't find any info. I would sincerely appreciate any suggestions to help resolve this problem. Thank you! Chuck

 

It is a pretty important Windows system file.

If you can, I would try reinstalling SP2 to see if this helps.

 

Thank's for your reply. I have downloaded sp 2. This didn't help I've gone to micro soft still can't find any answer.Also I up graded form (MB) Mach Speed.P43.0 to Intel (MB) P4 3.2 . Same Harddrive. In my general information it showes two CPU's I have noticed doubles of a few other things. Any Ideas ? The computer is up & running but I'd like to fix this THANKS Chuck