I had the same problem PsychoSword, or IE would just freeze, with 100% CPU usage, then I'd have to kill it. Easiest fix was to uninstall 5.5. and go back to 5. I think the difference between 5 and 5.5 is pretty small, not as if you get a dozen new features or anything.
MS seem to have a weird mentality - We have something that works relatively good, now let's fill it with shit and see if we can get more money outta it!@