um when u are restartin comp hit f8 and then pick safemode with command prompt but getin the command and renamin the system32 folder would kill the os and u proly would not be able to do it anyways but ya
but u can try this restart comp and then hit f8 and then pick "last known good config" k and see if it boots up also do u know if both was in the C:\Windows\System32? cuz if so thats normal if it was in a diff place ya then u got a virus
but also vista will have 2 runnin so if u are on vista then ya
oh and also if u cant get it to go with the lastknown good config try and do a system restore to a date that was good k here is a link to do it in safemode
http://support.microsoft.com/kb/304449