vbulletin problem after change server

[IRANCITY]

hi dear
i have transfer my forum
but after it i cannot login to site .... me & user can not ..
when i go to admin page and login i redirect to home page !
when i login into home page it's not login and show again home page
i use tools.php ... but it can't solve my problem
i change config.php perfix cach from bb to bb1
it 's not solve my problem ...
some times i give this err :

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

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

i user this in config.php but it's not solve my problem ....
define('DISABLE_HOOKS', true);

--------------- Added [DATE]1331203339[/DATE] at [TIME]1331203339[/TIME] ---------------

help me plz ...