I've been having the same problem. I have a 2.4 with 768 mb of memory. Even if that is the only thing running it will make my cpu usage 100%. Looking thru the forum, it looks like several people have the same problem, I'm using LW basic. Another thread mentioned checking you incomplete downloads, but I have no incomplete downloads either indicated in limewire or in the incomplete folder on my hard drive. When I start it up it runs just fine, but after about 5-10 mins it goes to 100% CPU usage.

I've been thinking about upgrading to pro and I used to leave my computer on with limewire running, But I can't do it when it's like this. Hopefull the people from limewire will read this thread and help us all out.