Me too... pokerstars + party poker + pokertracker/pahud + AHK hotkey scripts.
Have been going crazy for ages about this, it has happened in every single build up to 3188. Unsure on whether it's caused by pahud and pokertracker or the poker site's programs, but if lots of other poker players are using it it's likely that it's caused by some of the utilities we use.
I have had it happen when multitabling stars + party. 1970 works great but it's pretty slow graphics-wise in comparison and coherence is nice using multiple monitors.
Another problem I've had in the past is when importing things in poker tracker as the mouse changes between regular cursor and busy cursor back and forth a lot. This used to cause my whole computer to lock up under 1970 (windowserver at 100% cpu and graphics corruption, but able to login remotely to reboot it). If I minimise pokertracker to a tray icon this does not occur. This bug is the same bug as exhibited when people try to use the webex conferencing software (a problem which is supposedly fixed in newer builds, but I think is only really worked around).
I heard that upping the amount of reserved memory that parallels uses (rather than using automatic memory) fixes some unexpected errors, however I haven't tested this setting thoroughly enough to know whether I'm crash free yet.
Fusion has worked nicely so far, however exhibits worse performance in general than 1970 so isn't a solution yet.
Maybe you guys can chime in on how you use it and maybe we can isolate whether it's a tool that we're using or the poker software itself.