I apologize if this has posted before but I thought I would mention it.
I had the following work unit:

nh205_ 00017_ 5-- x-8 Pending Validation 4/19/10 11:00:51 4/22/10 10:43:06 11.65 103.5 / 0.0

get hung in one of my systems. It is a system which I only check every couple of days and it is only periodically connected to the internet. When I did check it it showed this work unit at 27% done at 32 hours of run time with 36 hours to finish. I knew this was either wrong or it was a huge work unit. I watched it for a short while and saw no progress. I exited BOINC and restarted my system. After the restart the unit sat at the same 27% done until BOINC finally got its bearings and then it went back to the last checkpoint at 25%, reset its run time to about 3 1/2 hours and showed 5 hours to completion. After this it appeared to run normally, showing continuing progress past the 27% mark, so I left it alone to finish. It appears to be OK at this point. This was on a 3.4ghz HT P4 with Windows XP Service Pack 3. The second jobs running in the other thread experienced no problems. Hope this helps someone else if they experience one of these.

Cheers