So, clean XPSP2 install from OEM Slipstream CD.. Updated Intel Chipset Drivers with latest from Intel. Updated Nvidia Drivers with latest from Nvidia. Updated Audigy Drivers with latest from CLabs. Updated NIC Driver with latest from Intel. Run WUPDATE and installed all Windows Updates. Installed MS Office 2003. Installed NAV Corp. Installed Acrobat Reader 8.0 - It finishes the install cleanly, icon appears on the desktop, PDF files associate and change their icon. But the PC won't launch reader at all. Double clicking a PDF, or just running the EXE, it just won't launch. I tried installing in XP Safe Mode as well, but the installer doesn't like doing that. It installed fine on my laptop (XP 945GM), on my work PC (XP 915G) and work testjig (Vista Ult Q35). The only major HW change I can see between the home PC and the others is that it has a pair of Raptor 150's running Raid 0 as the OS Drive. Any ideas FOAK ?