It started about a month ago when my graphic card driver (to GeForce 320.49) and DOTA 2 both had an update. After updating I was unable to play anything on steam as they all behaved the same way:
The application would crash as it attempted to open.
At the time I tried doing some basic stuffs to go around the problem such as re installing steam and the games, and role backing the driver. I also followed some more complicated solutions that I didn't quite understand around steam forums.
None of which worked.
After a while I read a post that suggested opening the games in compatibility mode. It worked, for each game that I set the compatibility mode (I did to Windows XP SP3). So I didn't looked much further.
I don't notice anything different in the other games, but DOTA 2 in compatibility mode got a bad habit of crashing, specificaly when:
-A match was found and the game starts loading.
-When closing Hero selection screen after pressing Play.
-Randomly during the game, but usually during fights. (This one creates mdmp files of 0kb with "(failed)" in the name).
As a side note I use Windows 7 Ultimate, have DirectX 11.0, updated the Graphic Card Drivers again to 320.49
CPU: i7 860 2.80GHz
Graphics: GTX 260 (1792MB)
Memory: 6GB DDR3