Just putting in my 2 cents here.... I also had that happen to me a while back when I was using Media Library. If I had too many categories the script would "choke" the server and CPU laod was always high. Not saying it's that script in particular but saying that this can happen with some mods out there. I would go with Lynne here and disable all mods, try adding:
PHP Code:
define('DISABLE_HOOKS', true);
right before the
Of your config file. Before doing so check the loads then try this and then check the loads again. If nothing changes it could be a configuration on your server that's causing this, try restarting your server (kills all processes that might be looping). vBulletin on it's own with no mods is EXTREMELY stable , any host that tells you other wise is full of it. In any case good luck mate. Hope you get your account back in order.