Shaw cable is known to filter p2p speeds which may be applied to individuals. That might not apply to you.
Your McAffee firewall should probably be removed to be on the safe side if it's no longer functioning normally. Firewall configuration to give LW full access: http://www.limewire.com/english/content/firewalls.shtml
Do this test: Bug Report instructions & sample image If false then you have some type of firewall issue which will either be due to your comp firewall or modem/router.

Sometimes simple fixes can repair things: Try deleting your LW Preferences folder whilst LW is closed; instructions here: Fixes for Limewire

LW can use a lot of ram or cpu depending on how it's used. There's things you can do to reduce it at least. Updating your Java to 1.5 might help. Not resuming all your files using the Resume/Find Sources button will help. Disabling ultrapeer abilities. Setting uplds & downlds for autoclear. After opening LW wait 10 to 20 mins before using. Let it settle down 1st. For more hints you can search the forum.