the F@H folks added this for ya too, computerruler.
"How is he shutting down the client? From the log, it appears that he is not properly shutting the client down since there is no shutdown message, and that could be the cause of the work unit corruption. Make sure he is shutting it down with CTRL+C and not letting Windows shutdown sequence shut it down for him."
I used to just X out the windows before I heard Ctrl + C was the proper way to do it, and I never had any problems.
Not the best time to be troubleshooting folding, though. Lots of people are having problems acquiring work units. I myself have got one of my smp clients and my gpu client to run, but the other smp client just keeps saying attempt to get work failed, waiting to retry. Not sure which clients/OS's are affected, currently.