Yeah exactly the same thing with mine, even if you end task the program you realise your system is still dead slow - then you check to see what programs are still running by doing CTRL-ALT-DEL and there it is still running at 99%

I've tried LimeWire now, Bear Share, and a few other program and have to say Xolox is the one I like the most it's simple and it resumes links well - It's only this one 99% CPU Utilization problem that dogs me and makes it virtually unusable.