I've found that if an open file's buffered contents are flushed to disk and then immediately moved (overwriting a different file), the move has a significant chance of resulting in an if Norton's AV protection is on and the file being moved is not excluded from being scanned.
Presumably this is because the flush is triggering Norton to scan the file (or marking it as changed so it wil be scanned on next access) which ends up in the file being locked for read when the move occurs.
Is there any way to work around this?