Corrupt files when installing Vista 32bit SP2

Each time I upgrade, SP2 downloads and starts the install process. At some point during "Step 2 out of 3" the screen goes black and files start being checked. File # 743 (riched20.dll) is found to be corrupt and an error is given. Sorry, I did not copy down the error #. Nothing can be done at this point other than to do a repair w/ the Vista CD and wait almost 8 hours for a restore to complete.

I have tried this 3 times so far with the same results. If I run a full chkdsk, about 30 DLL files (all of which are located in c:/windows/system32) are found to be corrupt. Chkdsk repairs these files only for them to be corrupted the next time I try to install SP2.

Anyone ever seen anything like this?

Thanks in advance,

Tony