1&1 Internet: Disk quota exceeded (122) error on MYSQL Database apps

I just started receiving the the following errors on all my websites hosted on 1&1 internet that have MYSQL databases.

Warning: session_start() [function.session-start]: open(/tmp/sess_x, O_RDWR) failed: Disk quota exceeded (122) in /path/page.php on line 20

The result is that no session is created, so things that require a session don't work too well.

Since I am nowhere near my allocated storage capacity, I'm not sure why this is occuring, and feel pretty confident that 1&1 support won't tell me, even if they know. The support people that I've talked to so far don't even have root access to the server, so I hope they fix it sometime soon. The temporary workaround is just to point the session.save_path somewhere else.

Luckily I use 1&1 for development only, as they are not reliable enough to host client websites, so no customers are effected.