Just a couple of thoughts:

I've been having this random inability to upload WUs also. 1 thing that works sometimes on GPU2 is closing the client
and restarting it.

Another thought for those who also run Boinc: GPUGRID.net now has a
GPU client for Boinc. Its not completely....what?....Stable?...No, that's not the word. I don't know....it
can be somewhat of a pita, I guess. But there are work-arounds and they are seriously working on the client.
It runs pretty well overall...with a little bit of understanding. Anyway, anybody that interested in filling in some of
the F@H down-time with another GPU client should check it out. There is an XS team already. I'm #1.....uh....out
of 2 active and 4 total. Anyway, I've no doubt that they can use the help with getting WUs completed and
feedback on the forums would be a big plus...no doubt. If anybody decides to check it out and needs
some help--just let me know.