I'm not over certain about this, somebody else will know better,
but whilst you are transfering files the program may use your TEMP
directory or some other directory to store the files in, if this
directory gets full it may be that which is causing the problem.

It's worth checking the amount of room you have allowed for this, and
increasing it if necessary, also possibly making a new directory for
it, checking if the drive is full ETC.

Sorry if I'm teaching my granny to suck eggs but I can't think of
anything else at the moment exept that you are running out of room somewhere.

Hope this may help a little.

Good luck with the problem.

Cattail !