100% cpu usage

[Silver24]

Hi all.
I have been using limewire for a few years now & have had no problems.
Now when i start up limewire it runs for a few min downloading @ great speeds then all of a sudden the speeds drop down to zero but still say im downloading from how ever many hosts. My CPU usage goes to 100% & the computer slows really bad. If i leave it for a while it does go back to normal running but then repeats its odd behaviour again.I have cleaned with AdAware, Spybot, Windows Defender, Spyware Doc, but found nothing. I was using version 4.14.12. I have uninstalled java & re installed Java but still the same problem.
Im using windows xp.
Virgin cable modem
1.5 gig ram
600g hard drive
Mcafee internet security.
When cpu is 100% computer runs really silent. Then when it goes back to normal you can hear the processor really working overtime.
If anyone can help it would be appreciated. Or if you need anymore info about my system set up. Just ask me.
Cheers Dave P