Uninstalling LW will not get rid of the file. All the files in your Library are just a reflection of what is in
Program Files>Limewire>Shared.
Have you tried associating your files with a different player to see if that solves the problem.
Other than that - I can't see a solution.
There was someone who actually found something to get rid of these files - I'll have a look if I can find the post but it's a heap of posts to search.
In the meantime - if anyone has a clue about this prob
