You'll need to check whether there's a SITCO firewall in place. Sometimes there's an option to change the level of firewall protection (eg low, medium or high)...you'd have to find out about that from your ISP.

Just because your friend uses the same ISP, doesn't necessarily mean that you have the same plan, the same options, the same download allowance, the same features with your package....see what I mean?

Something you could try is deleting LW's preferences folder when LW's properly closed. See point 3 here & also point 2 (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.

If you find that you don't have an ISP firewall & if deleting the prefs folder does nothing...send me a PM & I'll give you a link to download an earlier version of LW. Some versions behave strangely for some people.