Using the standard XAMPP distribution for Moodle 1.6.1+ from Moodle.org, 2 or 3 times a day I get the following error in the Application Event log:

Faulting application apache.exe, version 2.2.2.0, faulting module unknown, version 0.0.0.0, fault address 0x018882a0

I have set the Apache service to automatically restart after 0 seconds, so users don't observe an interruption, although caches need to be rebuilt.

I am running on a fast duel-processor machine with 2GB of memory running  Windows Server 2003 with all updates.  It does not appear to be load dependent.  We are running about 400 users at a laptop high school, at times with 100 students using Moodle actively at once.  But the crashes seem to happen at random times with a light load and nothing unusual in the Apache logs.  Memory does not seem to be low at the time.

I made a fresh installation of the operating system, but this did not resolve the problem.  While I do a number of things to tune the server for our load, I get errors on a test installation with no tuning.

I am suspecting that the version of PHP 5.1.4 is a little buggy from what I have read and may try to go higher or lower in version to see what happens.

But I am interested if others are seeing this in their Application Event logs and, if so, if they have found a way to address it.