random CRASH/BSOD after loading game/section

[QUINTIX256]

Black Plague on steam...

Many times I've recieved an "access violation" error message... sometimes newton is listed in the call-stack, sometimes just penumbra is listed in the call stack.

I've gotten a BSOD twice. Both times the message given was
"A clock interrupt was not received on a secondary processor within the allocated time interval."

Error also posted here, but I'll repost here just in case.

Catalyst 11.6; all other drivers are lattest available from Gigabyte.

4 GB 233mhz (1866mhz effective) Crucial Ballstix system memory
Windows 7 64bit SP1
Gigabyte A75-UD4H mainboard
AMD A8-3850 fusion APU
AMD Radeon 6670 from XFX with plain vanila 200mhz DDR3 (not GDDR3) memory (1600mhz effective);

Switching from the 6670 to the internal 6550 seemed to help abit (crossfire is disabled)

Catalyst AI is disabled, all other settings as recomended in the FAQ.