Hi,
We are looking into the issue. It was a result of yesterdays major upgrade issued by vbulletin.
I will post an update shortly when resolved.
Thank you for your patience
Vbulletin Response:

vBulletin Lead Developer Product Manager
Mod and plugin authors - the changes in 3.6.10 and 3.7.0 RC4 will break any forms in your code that post back to vBulletin scripts.
However, it is simple to adapt your code to include the new security token and restore full functionality.
Information about how to do this has been passed to the vBulletin.org staff, and they will be releasing that information shortly.