I'm not as sharp as I should be with error logs but any problem after reinstalling would mean to me that you've not updated the httpd.conf file to link PHP in properly. E.g.,
Hmmmm, My PHP installation commented out my bits and added their (same) bits to my httpd.conf. Go figure. That (PHP install) should obviously be done AFTER installing Apache.
#LoadModule php5_module "C:/PHP/php5apache2_2.dll"
AddType application/x-httpd-php .php
#BEGIN PHP INSTALLER EDITS - REMOVE ONLY ON UNINSTALL
LoadModule php5_module "C:/PHP/php5apache2_2.dll"
#END PHP INSTALLER EDITS - REMOVE ONLY ON UNINSTALL