For the record, here are the steps I go through to make sure I'm starting clean in Jaguar (OS 10.1.5 should be similar I think)
Run the LimeWire Uninstall program, then search for the visible and invisible Limewire prefs (search term "limew" usually pinpoints the folder to trash)
hold shift on a restart to boot in safe mode , repair permissions and if really on a roll, reinstall java 1.4.1 The java reinstall loads older versions, and doesn't take that long, so seems like a good idea anyway.
If downloads gave too many error messages and I'm desperate, I'll also trash the incomplete folder, especially the downloads.dat file. (I don't like this step, because trap_jaw has been working on partial file sharing, and I hate wasting partial downloads).
Then a reboot, and I try to make sure that Explorer downloads a fresh copy, not a cached one.

If none of the above help and others can install, then creating a new admin user or the ridiculous Apple Tech advice to reinstall the system is all I can do.