This might help: Fixes for Limewire As long as it's not a firewall or modem/router with a NAT firewall or you're connecting thru a company or school network which all may have different solutions. Oh & also hoping your isp is not filtering or blocking p2p use.

Knowing these things generally help with solving these issues: Can you give us a total desciption of your set up:
1. Operating System version (eg: Win 98),
2. What firewalls you have,
3. ram, 4. HDD space available,
5. Connection type,
6. Modem & router brand name & model numbers,
7. Where are you trying to connect from (home, school, work, etc.)?