SQL error and I don't know how to fix

[inspiration100]

When I go to vbulletin options under General Settings I get this error:
Database error in vBulletin 3.7.4:

Invalid SQL:

SELECT setting.*, settinggroup.grouptitle
FROM settinggroup AS settinggroup
LEFT JOIN setting AS setting USING(grouptitle)
WHERE settinggroup.displayorder <> 0
ORDER BY settinggroup.displayorder, setting.displayorder;

MySQL Error : Can't create/write to file '/tmp/#sql_ff0_0.MYI' (Errcode: 30)
Classname : vB_Database
MySQL Version : 5.0.67-community

Can anyone help me figure out how to fix this? I've tried disabling all my plugins and I have no clue when this error arose.
Thank you.