If you using an ATI Radeon 4900 or 5000 series card (e.g., 5770, 5870, etc.), you are probably getting a CTD after a varying amount of time spawned into the game. Our lead graphics programmer is working on solving this issue, but some players have found a possible work around.
ATI has also just released a hotfix for the 5800 series.
5800 Series Hotfix
If you're using one of the ATI Radeon 5800 series cards, and getting a crash, try this hotfix for the Catalyst 10.1 drivers:
A hotfix for the 5700 series cards is in progress.
CTD Work Around
Some players with 5000 series cards were crashing to desktop and then receiving an "Out of Memory" error, displayed in a SmartHeap message. Several have now reported that when they hide the Game Info HUD element (which displays FPS, Time, and other things in the upper right of the screen by default), they don't crash.
Please try this to see if it resolves the issue for you. Just press Num Lock once spawned in to hide it.
Our programmers are now investigating this work around to see why it works so that we can implement a solution.