P2P stands for Peer-To-Peer. P2P applications are Limewire, Bearshare, Azureus etc. Anything that will allow you to connect and download/upload from other users.

Do the test anyway. It's more to test your ISP than anything else. They might be blocking ports etc. If it says true then they're not

In some firewalls you have to make new exceptions for Limewire if you update

So you're saying that it doesn't open at all now right ? Just the splashscreen then nothing ?

Could sound like a Java Problem. Try downloading Java 1.5 update 6 (the offline version) then remove your current version and install that one instead. Just don't know why a Windows update would currupt the java

Also if you have an older installer for Limewire saved somewhere then you could try downgrading again

Don't you get a errormessage when Limewire stops loading ?