Turning off vB kills my main site
 

Not entirely sure if I should be asking here but anyway:

I have a joomla site. It is not bridged with vB (both are hosted on same server, different databases). When I turn off my vB forum (in the adminCP) it kills my joomla site (I get maximum execution time errors etc.)

Why would vb be interferring with my main site like that?

Hmm...I have a hard time imagining why that would be unless the joomla site somehow interacts with the vb site. You say it's not bridged and they have separate databases, but is the joomla site linking to or calling the vb site to get content?

I suppose it's somehow possible that the vb site is using excessive resources when it's closed. Do you have any way of looking at the processes running on your server?

Do you have the vBulletin forum set inside the Joomla wrapper? If so remove it from the Joomla wrapper and that probably will fix any errors.

If not are there any error messages? Have you check your server logs ?

The only thing I have is an RSS feed showing recent threads from vB in a module in Joomla - I'll take a look and see if this is the link causing the issue

That very well may be. Let us know.