Start by trying this:

1. From the Start menu, choose "Run".
2. In the resulting dialog box, type "telnet 64.61.25.171 6346". Click OK.
3. A window will pop up. If it doesn't say "GNUTELLA OK" within a few seconds, your ISP is probably blocking Gnutella traffic. In this case, there's not much we can do. Non-Windows users can run this as well if they know where to find the telnet program.