this the same situation I'm dealing with- I'm using OS 9.1 and limewire 1.7c and get the same thing - I'm on and downloading and then all of a sudden all my downloads just stop-no warning, no type of message- and i can't even get back on the system for about 6 hrs.

I have done some research and apparently we are the victims of some spyware on our macs. I posted a question about mac anti-spyware this week but so far have not gotten any responses, only views. The FAQs recommend downloading a program called Adware, but that's for PCs only.
I emailed the moderator, TuStarWarrior, and he said he would also look for something for those of us of the mac persuasion.
Keep your fingers crossed.