Can't alt-tab back into the game

I can alt-tab out of the game just fine, but I can't go back. I try clicking on the game and it just sits there like a bump on a pickle.

Guess I can play windowed mode until then, but it'd be nice if this was fixed for real.

What are you system specs?

Here's some relevant tidbits. Game runs like a dream on these specs:

• Core 2 Duo E8400
• 4 GB RAM
• ATI Radeon HD 5770
• LCD monitor running at 1920x1080.
• Windows 7 64-bit
• I update my Catalyst drivers, but not religiously, so I'm probably rocking few-months-old drivers. No specific version number off the top of my head.

I'm on lunch break right now, so I can't give you anything more specific unfortunately. If there's something specific you want to check on, let me know and I'll check when I get home.