I have installed Mountain Lion on my laptop and desktop computers. The laptop is fine. The desktop, one of the first Intel Macs, (Quad core Intel Xeon) is behaving weird. Itunes,uTube even Chess will not work but Pages, Calendar, Screenwriter will? The internet is working but slow. I have repaired disk permissions and started in safe mode but still the same. I have a Prism Sound Orpheus firewire soundcard and tried reinstalling the driver from the Prism Sound site but Apple would not allow this as it is from "an unidentified developer." I can't get into "Sound" in System Preferences "System Preferences not responding" Everything worked fine before installing Mountain Lion. The fact that there is no sound led me to believe that there may be a Soundcard conflict as my laptop uses no soundcard and works fine. I don't dare try the Orpheus with my laptop in case I lose that as well! Any help out there? Thanks in advance.