Take a look at this case: Both Protoss and Zerg don't have the ability to gather resources anymore, Nexus and Hatchery are destroyed. Protoss still have a few base up. What's left of Zerg's base will eventually die because there's no more creep. The game detected stalemate even though the Protoss is set to win? Is this is a bug?
Here's a link to the replay: http://depositfiles.com/files/kzonxjxh4
Fast forward to the end and you'll see the Zerg's base is dying on it's own and Protoss should've won.