I did this - was downloading *.iso files ( 3 pieces with each more than 3 GB size) - then I wanted to write e-mail with thunderbird. Thunderbird refused to send the e-mail with error - report like :
"sending of message failed.
error while writing into temporary file."
Then I tried to install and --reinstall thunderbird, but this did not help.
So then I deleted the .ICEauthority - directory completely and restarted the machine.
Then thunderbird is working like a charme again.
Should I empty the /tmp - directory completely ? - is this without danger ?