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[Diesel,]

Your submission could not be processed because a security token was missing or mismatched.

If this occurred unexpectedly, please inform the administrator and describe the action you performed before you received this error.

People keep getting this error on my forum, any idea what this is about ?

[Jase2]

This is most probably caused by an hack. Have a read of this: http://www.vbulletin.com/forum/showthread.php?t=268862