When attempting to use the quick reply button it works fine until I click on the 'Post Quick Reply' button. The browser becomes busy, but so far it has never actually posted the quick reply. It just stays busy until I eventually Quit and decide to go back to using Safari for this site.
The 'Go Advanced' button works correctly, as does the advanced reply page and anything else I've used on the site.

In Safari it's fine. Click the quick reply and it goes through within a second or 3 (depending on the speed of my connection). It's also fine in Firefox (the mac version).

I'm not sure if this is an issue with all distributions of Opera or not. I can test it out on the linux version in a few weeks time, once I have it installed.

Good luck, it seems like the sort of thing that could either be extremely simple or extrememly complicated to fix. Hopefully it's something simple!

I'll try to do an upgrade to our version of vBulletin, but I'm not sure if everything we have is compat. with it, so it might break some things -- which is why I hesistate to upgrade it.