I don't mean to sound trite, but are you running Windows XP?

I'm tearing at my limited hair here trying to figure out why you're having problems with bandwidth and inexplicable Internet activity, and it occurs to me that XP has this "thing" about making sure that you can't lose connectivity on those programs that are installed. XP is such a "nanny."

LimeWire isn't a problem for me under XP because I have a fast Internet connection and expect XP to help me use it. If your connection is of limited speed, then XP may be a handicap.

I am only guessing, here, but my uneducated guess is that XP has remembered your Internet settings and your LimeWire settings and, in order to protect you from any sort of loss of functionality, made it impossible for you to either slow down or shut off the Internet connection associated with LimeWire.

XP is funny that way.

Try totally uninstalling LimeWire, and reinstalling it from scratch. If you have incomplete files or incomplete downloads, then copy those folders to some other location on your hard drive, then start the uninstall process. Then copy the incomplete folders back into LimeWire.

NOTE: LimeWire is kind of buggy, so this advice is not unwarranted.

I very much doubt that this advice will help you, but it's worth a try, if you're willing to take a risk. Uninstalling and reinstalling software is never harmful.