Your ISP is whoever you pay for your internet.
Is your ISP Liberty Cablevision? Something's blocking LW's default port, could be your ISP. Other people have had trouble with Liberty Links (traffic shaping) in Puerto Rico in the past but I'm not sure if that's the same as Liberty Cablevision...maybe they've had a name change? Anyhow, I can't find any info to say that they're blocking p2p but since that test page won't load...it's not a good sign. Try the tips below, but if it's an ISP issue there might not be much you can do.

Make sure that you've allowed LW access through the OneCare firewall.

Try changing ports. In LW go tools > options > advanced > firewall config. Change LW's listening port to 64049, or something in the range of 49152 - 65535. Click Apply to save the change.

What's the model of your Belkin router (look underneath if there's no model showing on top)?

Try this version of Java. Use the JRE offline installer & remove your current Java version before you install this one.
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11

Try deleting LW's preferences folder when LW's properly closed. See point 3 here & also point 2 if you've used older versions of LW in the past (there could be a folder in either location).
Fixes for LimeWire
This will kill all of your settings within options, you'll have to go back through afterwards & reset things. If you're not sure of your settings, go through LW's tools > options & write them all down, so that you can reset things later.

See if the LW Beta version will connect. You can download it from the usual LW download page.