2 problems, might be related

1. when i try to download the critical update, it does
and tells me that it is successful, but everytime i come
back, it is available again, i have downloaded so many
times!!!

2. whenever i reboot my computer is says that it just
recovered from a serious problem, so when i track the pb
and submit it, it tells me it is from a driver, but i
can't figure out which one it is ???

please help!