Are you out of disk space or free inodes? Check in a terminal window for free disk space using: df -h Check for free inodes using: df -hi (this not likely the problem but still a possibility) If out of space or inodes delete some files (your browser cache is a good place to start) or move them to another partition that has free space.
Are you having disk problems? dmesg will display some kernel log info. Also see: /var/log/messages (must be root to see)
Did you rename, move, or remove the directory that you were saving to?
No, no and no. It is a quite freshly installed FC4 with almost 100GB free on the /home-partition.
Should definitely not run out of anything.
But thanks for the answer!