FYI, I have found several tasks running 3+ hours over the past week. This is across 3 different machines with XP64, with both 4870 and 5870. Interestingly enough, I have not seen this with my dual 5870 machine (remember a task runs across multiple GPUs if you have them). I aborted them, and the following tasks crunch regularly. I am not sure what is causing this recent issue. The issue could be with the tasks or maybe the drivers. I think MS updated the drivers with the latest monthly update.

So heads up, and keep an eye on your machines so you do miss out on credits due to a messed up task.