Blue Screen after dedicating video memory

New system, ZT systems, amd phenom quad core, 8g memory, onboard video ati 3100, when I go into the bios and turn the video settings from auto to 1g, opening screen comes up perfectly, enter password, flash as it goes to desktop and blue screen. If I change the video setting to anything below 1g it works perfect, but system performance is below average. ZT tech support says its because I'm taking an entire gig of memory out of the dual channel memory....doesn't sound right to me...any input will be appreciated.

ok here's the latest minidump report. please let me know if i didn't do the attachment correctly.

Your dmp file shows your error as PFN_LIST_CORRUPT (Page Frame Number)

This bugcheck usually occurs for one of two reasons, the first reason being memory corruption. If there is a buggy driver in the system that is writing on memory that it does not own, it could easily corrupt one of the PFN lists or entries. In order to rule this out, you should run Driver Verifier with Special Pool enabled for suspect drivers in the system. This will hopefully allow you to catch the misbehaving driver in the act of scribbling memory, instead of receiving a crash sometime later when the O/S discovers the damage.

Download memtest86 and allow it to run overnight... let us know how it comes out...