numerous exe’s generated errors and will be closed by windows

Windows 2000 PRO almost anything I try to run gets the message: xxx.exe has generated errors and will be closed by windows. Tis happens for apps like winword, to things like mmc, msth (whatever the add/remove programs exe is), etc. I don’t think it’s a virus or spyware as my programs didn’t turn up much. I ran SFC (after I finally got it to run!) /clearcache and /scannow – neither helped. I’ve seen this problem before.. People write in when they get it on one exe.. but this is many.. There must be an answer. Help would be much appreciated.