A sign that someone was hacking into my computer?

Two nights ago, I was downloading a bunch of songs from Kazaa Lite and all of a sudden on the upload part, there was someone downloading a 600mb file from me. The thing was, I disabled file sharing and how in the world would that person be able to download from me? Plus, the speed that person was downloading from me was insane, it was going between 1500-2000 Kb/s which is crazy fast. I don't get it, after it was done uploading, it still kept uploading, like pretend the file to upload was 600mb, it went past 600mb and just kept going up. Now, I started getting pop up messages out of no where say people can get into your computer and use your files blah blah and stuff like that. The message tells me to go to www.stopmessenger.com and a couple of other websites which I forgot. I'll post it up when I get the message again.

I have Comcast Cable Modem and I'm wondering if there anyway I can detect how that message keeps popping up in my computer and what software can I use to stop intruders from hacking into my computer. Thanks!

Also, if it was really downloading that fast, it was probably someone on your local cable node or very close in your neighborhood.

I know in Imesh lite, when you disable file sharing people can still download files in your download folder, even partial ones that haven't come in all the way. So when my files finish I move them out of my main folder. I don't know if kazaa lite is similar.

You'll also want to make sure you have Antivirus software, and a spyware checker like Adaware.

And a firewall is always recommended with cable, otherwise you are open to attacks, or virii from people on the node.