iPrimus aren't blocking p2p. If you exceed your download limit for the month, you'll get shaped back to snail speed until the end of the month, but they won't stop you connecting

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

If that doesn't help, try deleting LW's preferences folder when LW's properly closed. See point 2 here & also point 3 if you've ever installed a newer version of LW (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.

Or you could try changing ports. In LW tools > options > advanced > firewall config. Change LW's listening port to 64049, or something in the range of 49152 - 65535. Apply to save a change. Any ports forwarded within a modem/router will also have to change.