"Unexpected Error" syncing to perforce

[ZooTroy]

I am doing a forced sync in perforce involving ~10,000 files.
The sync is completed correctly, but visBuild reports a step failure. The log file has the line "Unspecified Error".
If I split the sync into smaller steps, the error msg is not displayed.
Any ideas as to how I can prevent this error msg (aside from splitting the sync) ?

Thanks