I am also having the same issue. Receiving the following errors during file transfer:
552 Disk full - please upload later
Error: Critical file transfer error
According to the stats I only have used 0.36 / 250 MB space. I'll be keeping my eye on the thread, just thought it was best to let you know.
Cheers,
John
(P.S. - Just noticed it can transfer the folders fine, but when you try and transfer a file, this is where the critical errors occur.)