Whenever I try to install either 9.5 or X it doesn't complete and I get the following error message
"Error 1324. The Path Windows XP/Application Data or the volume is invalid."
Not sure; I have not seen that error 1324 before, but it sounds like some of your environment variables may be pointing to an non-existent drive or location.
Try the "Fixit" in http://support.microsoft.com/kb/886549