I have had similar problems with various games (DD was at the top of the list), where the game would randomly crash.... interestingly enough i found that corless mice had a MAJOR effect on it - my crash used to start showing "symptoms" of instability, where the mouse would refuse to move for a couple of seconds (my cue to save), then a couple of minutes (sometimes seconds) later, the game either freezes up, or crash to desktop... when i consulted the distributor company where i got the cordless mouse and keyb from, one of their major geeky (no offence, i LOVE geeks, they KNOW stuff)technicians, pointed out that some mice (especially cordless and some opticals - the more funky types, like trackballs and multi-buttoned ones) sometimes causes a "overload" in your windows swap file / virtual memmory. Some of the companies of these mice have a specialised driver available that stops this from happening, but others you need to increase your virtual memory (not let windows handle it).
I changed my memory handling and problem was resolved for MUCH longer aswell...
This may be why an external memory management program is solving (sort of) your problem until your virtual memory gets clogged up again.
Diablo 2, Revenant, and a couple of other RPG's had the same problem in the past.
Check with computer company for mouse driver updates (i know windows likes using its own by default, but some brands have better drivers available). I hope this will solve your problem completely, so that you too can discover at 5:30 in the morning... that "Oh Sh|t!!!!! i havnt slept yet, and i need to go work now !!!!"
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