Are you absolutely sure that you haven't made some other changes exept from upgrading

If not. One reason could be that you are using manual Port-forwarding instead of UPnP. The portnumbers may have changed

If you are firewalled you need to allow Limewire.exe to connect to the internet.

Its really hard to tell you what to do with so little info, but I tried

Also what version did you upgrade from ??