I have been getting some instability running Apache with PHP + Accelerators under Windows 2003. I will log my finds in this article. Visit regularly for updates. I ended up running 7 Apaches on a Windows 2003 Server to test all different kinds of configurations. Recently because it was becoming complex, I started logging my finds. This page is probably for the hardcore debugging type...

Mitigating factors:
- Most crash seem to happen because of load (with very low traffic you might never experience problems).
- My PHP applications are very demanding. Especially Gallery2 which relies on external libraries for processing images. Again other PHP applications might not experience these problems.
-If you have issues with IIS, these finding might also be applicable.

Configuration that appear to be stable:

Apache 2.2.3 + PHP 4.3.11 + ApacheLounge PHP connector +  eAccelerator 094 Sitebuddy_v2 for PHP 4.3.11
It's been 1 week now (9/21) with 2 sites running just fine. On instable "software stack" just 1 of these sites would crash multiple times per day.

Apache 2.0.59 + PHP 4.4.4 +APC accelerator (3011): Weird blank pages in VBulletin if setting apc.stat=0
very rare crash trying auto_globals_jit=On (with other 3 "register" Off) as been stable since nearly 1 week

Apache 2.0.59 + PHP 5.1.6 + APC_3012_SiteBuddy: Weird blank pages in VBulletin if setting apc.stat=0

Configuration that are possibly stable at this point:
Apache 2.0.59 + PHP 5.1.6 + xcache(1.0.2 re-released): very little load on this server
Apache 2.0.59 + PHP 4.3.11 + APC accelerator (3011): Weird blank pages in VBulletin if setting apc.stat=0
Apache 2.0.59 + PHP 516: very little load, so might not be accurate
Apache 2.2.3 (not using the new cache feature) + PHP 4.3.11 + ApacheLounge PHP connector
Apache 2.2.3 (with new cache feature) + PHP 5.1.6 + ApacheLounge PHP connector:  very little load, so might not be accurate

Configuration that are instable (note: I run "heavy" PHP sites (Drupal + Gallery2):
Apache 2.0.59 + PHP 4.4.4 + xcache(1.0.1RC1): rare crash
Apache 2.0.59 + PHP 4.4.4 + xcache(1.0.2):  rare crash (testing Apache 2.0.59 with PHP 5.1.6 now)
Apache 2.0.59 + PHP 5.1.6 + APC_3012: does not even enable the loading of a Drupal + Gallery2 site.
Apache 2.2.3 (not even using the new cache feature) + PHP 5.1.6

Apache 2.2.3 (using the new cache feature) + PHP 4.3.11 + ApacheLounge PHP connector: weird missing style sheet issue (Drupal + G2 site)

Got mixed results (need to look into details setting differences). Could also be due to the difference PHP extensions used.
Apache 2.0.59 + PHP 4.4.4: crash
 

Details (personal notes):
1)

2) This difference is most likely due to "Apache 2.2.3 PHP 5.1.6 No crash" has practically no traffic. Logging what I got just in case.