I had the same problem recently. I don't know the cause, but the fix is to re-install Lime Wire. First, move/save all your shared folders out of the Lime Wire folder - usually in program files); that way you won't loose them when you ...
... Uninstall Lime Wire completely.
Go to ZD Net (or other program download site) and get the new Lime Wire, or your older version if you can find it. Save it, don't open it - I put new downloaded programs on my desktop so I don't loose track of them.
If you choose Ver. 2.7, you will also be give an option to install an updated Java VRE - do that! Again, save it, don't open it.
Hint - open a new folder and call it Lime Wire Stuff, and put the programs you dowmloaded in it. Now they're available if you have future problems.
Install the new Java VRE first. Then, install Lime Wire and rock on!
This fix comes with my usual MONEY BACK GUARANTEE. It has worked for some, not for others. It's a pretty fragile program, and there are lots of variables between computers - GOOD LUCK!
Drop me an e-mail and let me know if this helped.
Pagester
the_pagester@yahoo.com