I have seen my client marked as hung also and it seems to be a problem with fahmon.
The client still folds normally and after it has folded three more frames, fahmon corrects itself.
It seem to happen when the client has just started, such as when I have just started the computer.
To check if your client is still folding, start Task Manager and look for the F@H client in the list.
If the client is using the processor a lot, then it is probably still folding.