[Zope] Errorno 2

Hi all I'm experiencing a problem, wihich I can't pinpoint. I've written a small external python script, which writes a logline into a sequential file. Nothing komplex. This gets called whenever a webpage gets called. Now I get the following error: IOError, Errno 2: File or directory not found: <filename>.log The thing is this happens when I have low traffic on the Z-box. The system is up an running for about 12 months now and it has happened twice in the last 14 days. The logfile is about 330Mb. Any ideas where I would have to start looking? Thanx Oliver