G5 2.0 Crashes. Apple stumped. Help please.

[Rickapple]

I have a G5 dual 2.0 (early 2005) with the Apple OEM ATI X850 XT video card, 2 gigs of RAM. It always crashes running CS3 and Safari. I have done the following: Zeroed the drive (7 pass), installed Leopard, re-zeroed the drive and installed Tiger, replaced the RAM (run in pairs in the correct slots, both Crucial and Corsair tried), taken it to the Apple Store three times, passes all hardware and RAM tests every time. (Also tried the usual suspects, PRAM, replaced battery, diagnostic utilities, etc.) No matter what, it crashes on Photoshop CS3 and Safari (complete lock up). Console reports EXC_BAD_ACCESS (0X0001) KERN_INVALID_ADDRESS (0X0001) AT 0X1b813a94. Here's the kicker... it will run forever if I start in safe mode. No crashes. (There are no after market start up or log in items installed.) What makes the difference? Memory controller? Logic board? HELP please. It's taken me five precious days and I'm getting nowhere. Any thoughts, please call me at 508-358-8105 or email rick.colson@comcast.net.