Sorry - I didn't read your thread title properly, so I didn't realise that LW was crashing before it even opened

Was 4.18 working properly at any stage? Which version of 4.18 do you have installed?

Right click on LW's desktop icon > properties > compatibility. Try running in compatibility mode for Win 2000 or NT.

You could also try points 1 - 8 here: http://www.gnutellaforums.com/333278-post2.html
BUT... instead of downloading a new LW from the link in point 2 (that will download the new LW 5, which a lot of people don't like), download 4.18.8 from this page: Lime Wire » Download Out-Of-Date Installers
Then follow the instructions in LOTR's post.

If you're happy to try LW 5 then by all means use the link in LOTR's post but just be warned - it's very different to LW 4

Can you remember offhand whether you had heaps of downloads on the go, last time LW worked properly?