problems with USER.EXE

i uninstalled some software today that went to my old web cam and when i restarted my computer a message saying “cmdninst has caused an error in USER.EXE cmdninst will now close.” then the computer stops and windows will not finish starting up. so i started it in safe mode and it finally started up. after that i restarted it and it started ok but hardly any of my programs would work. i had the cd’s for some of them and reinstalled them. but everytime i try to so something the computer will freeze up, and i have to restart. i tried to reinstall windows but is has another error in my USER.EXE program and it will not let me reinstall windows? does anybody have any suggestions