OK ive just spent 6 hours trying to fix this and in the end, the solution was so simple!
My pc had the classic symptoms:-
Limewire opening repeatedly, 15 seconds after it was closed.
ctr,alt,delete was not displaying task manager.
I found 2 'strange' folders on my pc, the 1st one was 257Mb and contained 1300 zip files each was 197K and contained one file and most were named after movies. The 2nd folder was very similar, but contained installer files.
Of course i deleted the lot immediately without unzipping or clicking anything.
I ran NAV,Spybot and Adaware.
Adaware found worm win32.p2p-Worm.Alcan.a
I deleted/quarantined it but everything was still the same.
I copied task manager onto desktop, so i could open it.
As it transpires, the offending process was masquerading behind the name svchost.exe (alongside 6 other genuine ones)
I ran msconfig and selected diagnostic startup and low and behold, the offending process showed itself in task manger (whilst in diagnostic startup)
The offending article was a install file called svchost.exe and was located in:
C:\Documents and Settings\All Users\Start Menu\Programs\Startup
I deleted the item and restarted my pc.
Problem fixed, no restarting limewire
I even opened limewire from the start button and closed it again to make sure, but its all good
I hope this helps somebody spending hours and hours like i have done today

TD.