Who da man?
In any case make sure avatars are no more than 100 pixels either dimension before trying to upload, other than that not sure what the problem may have been.
This was, indeed, the problem. Just tried it again after resizing it (was about 3 pixels too big) and it worked. I'll keep this one though, for Floyd
Sorry to have bothered, still, as a suggestion; it didn't say my pic was too large, just gave me an error, maybe something to update?