Have had similar problems in the past with Vista and being unable to save files from app's onto local drives, major weird file system stuff. I eventually learned it was COMODO Firewall causing all sorts of hidden changes to my existing file system. It's unfortunate, but jumping into that program without advanced knowledge of what it can actually do will put your computer at risk if your not careful.

There are definitely windows commands that can be run to unlock or protect these things from happening I'm sure of it, just I have no clue what they are. If your problem persists, you might want to go hunting down a better explanation. If its an isolated error occuring only with Limewire, then you need to try re-installing, changing options and tinkering until you see results...That's all I can suggest, its general knowledge, but I'm not a Limewire pro yet.