Forum loading only partially

[tutorialsphere]

Hello, I've posted this at the vbulletin.com forums as well, but nobody has been able to help me figure this thing out yet... Here's what's wrong.

I'm in dire need of some help here as I've tried everything to solve this and nothing worked so far.

My forum is here: http://www.tutorialsphere.com/forums/

For the past 2 days or so I have noticed a problem with it, which is that it's loading only partially. More than that, each time I refresh the page, it loads up to a different point than it previously did (i.e. once it loads up to the header, second time it loads up to the first forum and so on).

Does anybody have any idea what to do to solve this? Perhaps it's a cache problem, or maybe something else? I'm really not that much of an expert with this kind of thing...

I have disabled all custom themes and all plugins, yet the error persists.

Any help would be very much appreciated.

Many thanks,
Gabriel