Have had the same problem with Kazaa that you are having with Limewire. The first dozen or so times that I used it had no problems at all, though a little slow. But then it started freezing the whole computer, and the only way I could get out of it was to turn my pc off. I also thought if I forked out the money for the ad free version with the download booster things would be better. Not so. I wasn't even on for half an hour and it froze my pc. That's when I started using WinMX. Then I tried Shareaza, but it wouldn't even let me do searches, so turned to Limewire.
Have to say that apart from the auto disconnect, Limewire is by far the best application I have tried as far as searching ,storing, sharing and download speed is concerned. So I guess I will have to be prepared to monitor my pc until a solution can be found.
Did notice today that everything was working fine until I reduced Limewire to my system tray and that's when it started playing up.
Whatever you decide to do, unless you are prepared to risk blowing your dough, I wouldn't bother spending the money on Kazaa.