Hi. Been away from Tiki for a while.
Sounds like you have multiple issues going on. If you're getting stop script messages then that is a client side issue. I haven't used newer versions of Tiki in a while but I know that stuff was being Ajaxified. Maybe you could try turning that stuff off on your own website and see if that helps?
As far as blank pages loading, then I'm inclined to think that's a server side issue (assuming your Internet connection is reliable), in which case you want to check things like memory allocated to PHP and execution time-out length for PHP.
Edit: I meant to add that I've seen this kind of behavior with tiki.org too. I think it's because it's just a really busy site and gets absolutely hammered. At peak times I'm sure Tiki's host servers get a really good workout! ;)
I'm not an expert though, that's just my two cents.