I have the same setup as yours except I use WAMPserver, no problems, it could be related to xajax_0.2.5 try uninstalling it, if it works you know where the problem is, I am at work but once I get home I will install xajax_0.2.5 to see if I get the same problem or not.
Ok uninstalling the xajax did the trick... I wonder why it was there in the first place... But I once had some phil extensions installed, perhaps they were the once needing em...
I will see if it continue to works - thanks for all the inputs guys and girls