Thanks to everyone that has reported issues.

Seems the site is the victim of some of the 'strict' checks that I believe were introduced with PHP 5.4. Unfortunately vBulletin overrides (in almost every script) the system error settings, so when I turn off error reporting globally it's turned back on by individual scripts.

I'll look into this and hope that they release a patch fairly soon to sort it. I'm fairly confident there is nothing majorly wrong and that there are no conflicts between old and new versions because I completely cleared out the old scripts (and uncovered a number of backdoor scripts from our friendly neighbourhood hackers) and then installed the new version.

With regards to the AJAX chat script, I'll have to look into that and get back to you :-)