Also, my firewall says that apache is shutting down httpd.
That's because Apache (httpd.exe) thread safe is actually two processes when running properly on Windows. And the worker/'child' signalled for a graceful shutdown.
Because Apache for Windows is multithreaded, it does not use a separate process for each request, as Apache can on Unix. Instead there are usually only two Apache processes running: a parent process, and a child which handles the requests. Within the child process each request is handled by a separate thread.
First - are you using mod_perl for anything??? If not - try disabling it with the setup_xammp.bat or Setup in the XAMPP Control Panel. Its quirky and might be the cause.
If Apache is a service, you will want to reboot prolly, and see if everything is smiley
If that's not a fix -
Ok - its an upgrade - Did you move your files back into the document root?
Also possible you have a corrupt TCP/IP STACK (there's a non-destructive fix)
All just 'thoughts' at the moment.