[vranko]

I know nothing about the vBulletin software so take this advice with a grain of salt.

The site it probably complaining because the request you're sending is missing a CSRF token (Cross Site Request Forgery). Something in your browser or on your machine (add blocker?) may be manipulating your requests. The data in your browser's cache could also be causing issues. I would try clearing the browser cache. If you have another browser installed, try it. If that doesn't work then a Dorki admin will need to step in with advice.