wont run programs after install of sp2

I updated xp from SP1 to SP2 when I rebooted it came up with this error
"Stop: c0000221 {Bad Image Checksum}
This Image crypt32.dll is possibly corrept. the head checksum doesnt mach
the computed checksum." and turned off the Hard drive (Odd but it did)
So what I replaced "crypt32.dll" like MS says to. Every thing booted fine
and but when I tryed to get online to do some more updates IE wouldnt run,
nothing wouldnt run. I checked task manager only the programs where running
was the programs starting up, so I tested it and it would show for a slit sec
and close, so I figed somethings messed up With SP2 and went to system
restore to go back... and the samething happend as before.
So what could it be? I cant format and reinstall windows so thats out of the
question.
Thanks for the help, Ben