I have been having the same problems that I see being described so many times, but none of the proposed fixes have worked and in this thread, the problem is solved but we do not know why!
I have tried installing XAMPP/Apache on 2 XP machines in my home network with the same result - Apache won't start because (according to the event viewer) it cannot find the path specified. MySQL starts fine.
I have tried installing it on a VirtualBox and amazingly Apache started up, I saw the green 'Running' label and then within 2 seconds it switched off again and could not be switched on again! What could that mean? Something in my network?
I have done all the renumbering of ports and checking for another app using port 80 without any good result. The problem seems to be that Apache cannot find where to run from and where to write logs. So many responders to these questions tell us with the problem to look in the log file, but because the path cannot be found, the log file is never accessed and remains the same as what it was when installed.
Starting the Apache service from Windows Services interface, ends in "Windows could not start the Apache 2.2 on local computer".
I have seen that there appear to be issues with Comodo's antivirus, but people are seeing reports in their logfiles in these Comodo cases which means that the path seems to be OK. I have disabled the Comodo firewall and Anti-virus - problem still there. The Virtual XP machine does not have an ant-virus running, but perhaps the host's anti-virus detects something that the Virtual XP is doing and blocks it.