It's funny. I'm using Firefox 2.0 and I don't experience the problem you describe. I DO, however, have to log in with my username and password TWICE nearly every time. I have no idea why; Firefox doesn't ask me to remember the username and password either, like it does for most web pages.
I've done a fair amount of software validation testing too, btw.
I like the UI on this site (except that I wish everywhere it said "my" it said "your" because I am not talking to myself when I read a web page).
But there's something chronically unreliable about it in a specific way: about a third of the times I press a button, the browser activity indicator spins (I'm using Firefox) but nothing else happens. I have to refresh, re-do my move, repost my forum topic, etc. to get action.
It's become rather irksome, and I'm wondering if there's something about the underlying web architecture that causes it. I'm particularly suspicious of Google Analytics, since that often seems to be a place where the transaction hangs.
I hope you guys are thinking about this. This site has such great features, but I find that others are more reliable.
-- James Bach (software tester)