I've got a 1 Gig Tbird on a K7S5A with 256MB PNY PC133 in one DIMM slot (the right one). Whatever I put in the left slot causes lockups. I've used three different brands of ram in the left one and within minutes, my screen is frozen. Anyone have any ideas? The system runs great as it is. It's never once locked up. Put ram in that left slot and deep freeze. What gives? Actually, the 256 is enough for me but it just galls me that there's an empty slot sitting there.....