Data Collection End Activity Prowin32 error

We're in Vantage 4.00.904, and I have three employees clocked in to
different jobs/operation that get prowin32 errors when attempting to end
their activity. Have tried all of the following numerous times with no
success:

1. shut down data base, progress, and server and rebooted.
2. ran "endact.r" routine. The routine seems to run ok, but has no effect.
Have run it sucessfully in the past.
3. reindexed data base.

Am currently uploading db to epicor for them to examine, but if their are
any suggestions out there that I haven't tried, I would greatly appreciate
any help.

Also, any clues as to what causes the data collection problems in the first
place?
Norm