Make sure that you're only using 1 software firewall & that LW's being allowed through it.

Try the advice here: all of a sudden will not connect (a fix to try)
Start off by deleting LW's preferences folder & changing Java versions.
You'll know if you've deleted the preferences folder properly...when you start LW, you'll go through the setup wizard again & all the settings within LW's options will have changed.

If you're a vista user, things are a bit different for Vista when finding the preferences folder & other files/folders within Application Data. This thread should help with that: LimeWire Pref Folder in Vista

if nothing there helps, please give us your details.
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