Alright, sounds as if you have Mas OS X.

Go to the get info of the folder that you have selected to save/share. This is "checking file permissions". Make sure that all the users/groups who need to be able to read/write to that folder are able to. A "locked" folder is one that you can only read, but not write to. If the folder is locked, you will be unable to save information to it, but will be able to read it.

I think we're dealing with two seperate problems. One sounds simple, the other more difficult. The complete dls not playing is the simple one. Are you using Limewire's built in player? Or something else? This sounds like an easier problem.

Another possible solution to your library problem. Try chaging your save directory to something else.

A possible glitch I've read about (although only in Windows, and old too, but who knows, worth a shot) is that Limewire views a save directory as invalid if it has weird symbols in it (i.e. ~`) stuff like that. Make sure that the save directory and all the folders it is in don't have that.

Try placing a test folder on the very first tier of your harddisk. Just open up your startup disk and make a folder called Limewire downloads, go to your preferences and set that as your save folder. See if that works.

Report back and tell us how this works out.