I was running a "happy" installation of Apache (2.2.11) and PHP (some other version) with no problems on my development machine.
Then, one day, I felt like upgrading to 5.2.11 (PHP) and this broke my install. Now, Apache fails to run, and the Windows "More info" button shows that the erring module is "php4ts" or something similar.
It displays the standard Windows error message:
Apache HTTP Server has encountered a problem and needs to close ...
and in the "More information" section, it says:
Error Signature -- szAppName : httpd.exe szAppVer: 220.127.116.11 szModName : php5ts.dll szModVer 18.104.22.168 offset: 000f331b.
Apart from the stuff required to use PHP,
httpd.conf doesn't have anything notable. On commenting the PHP part out, Apache runs, but without PHP (as expected).