What you need to do is use a different theme. Not all themes work on all browsers. So what theme are you using, or if its custom, what did you base it off?
Some of the original themes are sometimes 100% more reliable i.e. olive or bluegreen. moreneat contains many hacks and is sometimes really a problem.
I have some custom themes at http://shop.damosoft.net/themes/ if your interested. Or I could offer some assistance to get yours fixed. I have Safari, Mozilla, FireFox, Konqueror and that thing called IE to hand.