Can you recall what the last thing was that you downloaded ??
More than likely one of those files had a corruption within it and now it has corrupted your shared folder...
The best thing I can suggest is to type the last few files into your computers search using keywords and delete the file when it appears, also make sure you empty it out of your recycle bin as well, do this one at a time until you can re-enter your shared folder...
This more than likely has caused a corruption in limewire's preference folder/s as well, hence not being able to get limewire to start up, so you will have to delete it and re-set your limewire configurations...
This sticky will explain how to delete the preference folder/s...
Fixes for Limewire when LW isn't operating as it should LimeWire Pref Folder in Vista
Also after all that is done you may want to run a full system scan with your AV and spyware apps...