Try deleting your LW Preferences folder whilst LW is closed; instructions here: Point #2 & 3 in Fixes for Limewire (sample image included at bottom of page.) Then try opening LW again.

Do you run any anti-spyware or anti-adware programs?

I've a suspicion the problem is your ISP. The best way to find out would be to try another gnutella program such as either FrostWire, Phex or Bearshare Lite.