Crossfire hangs again and again :(

It could happen when your computer's temperature is too high from heavy process, gaming actually makes it hotter. If heat's the problem, you can try playing with the system's case removed, that should stall it for a while.

Could also be excessive memory usage. Look at disabling some programs that might be running in the background. You can do this by: Press Ctrl-Alt-Del to bring up Task Manager. Click the Processes tab and select the program you want to stop from the list. Click the End Process button to stop the program. You'll want to stop any program that is running under your "profile" in the Process tab. "Local Service" , "Network Service" and "System" you'll want to leave alone..