How did you create the backup?
The only reliable method of backing up and restoring a database is with shell access via telnet or ssh. This is because backing up with a PHP script like that in the Admin CP or phpMyAdmin can result in PHP timeouts errors and an incomplete backup file. Please see the instructions here:
Backup:
http://www.vbulletin.com/docs/html/m...nce_ssh_backup
Restore:
http://www.vbulletin.com/docs/html/m...ce_ssh_restore
P.S. If you don't have shell access, some people have also reported success with these scripts:
MySQLDumper:
http://www.mysqldumper.de/en/index.php
MySQLHotxcopy:
http://www.vbulletin.com/forum/showt...t=mysqlhotcopy
Bigdump:
http://www.ozerov.de/bigdump.php