Suddenly unstable when inserting mem stick in slot 2

[Dancer]

I think I need to get a new motherboard, but wanted to post here in case I've come to the wrong conclusion.

System: ASRock 775Dual-VSTA "Conroe Presler", with Intel Core 2 CPU 6300 @ 1.86 GHz, Geil 1GB PC2-5300 DDR2-667 and Nvidia GeForce 7950Gt.

PC was working fine for about ~4 years now (upgraded PSU and graphics card in that time) but suddenly started freezing, rebooting (yes, I've turned auto reboots off but makes no difference) and bluescreening. I've done memtest and run chkdsk both without errors (actually there were "unrecoverable" errors first time I scanned the hd, but since then it always scans fine). I tried removing all usb units, additional drives and testing both memory sticks and what I found is that when I remove the 1GB memory stick from slot 2 it runs stable. If I move the memory from slot 1 to slot 2 it becomes unstable. Since it only has two DDRII slots this means I can only use one of the two 1GB sticks.

Anyone know how to fix this, or if not anyone want to recommend a good new mobo that will work with my CPU, GPU and memory?

Thanks

 

[Dancer]

Followup: I upgraded the bios from P1.9 to the latest (P.3...) and set the memory to flexibility mode and surprisingly it now boots and runs stable with both slots of memory. It also seems to have stopped the quiet fan mode from working as the fan is now working full blast all the time regardless of what targt temperature I set (core temp measures a steady 40-45 celsius).

Cheers