Database Errors after switch to 3.6.10

[SVTCobraLTD]

After switching to vB 3.6.10 I keep getting database errors. Last night I got about 13 of these... not sure what it means.

Database error in vBulletin 3.6.10:

Invalid SQL:

SELECT pm.*, pmtext.*
, icon.title AS icontitle, icon.iconpath
FROM pm AS pm
LEFT JOIN pmtext AS pmtext ON(pmtext.pmtextid = pm.pmtextid)
LEFT JOIN icon AS icon ON(icon.iconid = pmtext.iconid)
WHERE pm.userid=960 AND pm.folderid=0
ORDER BY pmtext.dateline DESC
LIMIT 0, 50;

MySQL Error  : Can't create/write to file '/var/tmpsql/#sql_a98_0.MYI' (Errcode: 13)
Error Number : 1
Date         : Tuesday, May 6th 2008 @ 01:29:14 AM
Script       : http://www.site.com/forums/private.php
Referrer     : 
IP Address   : xxxxxxxxx
Username     : xxxxxxxxxx
Classname    : vb_database