Give your ISP a call & ask them
why your port 6346 is blocked! Try to find out if they've started blocking p2p.
If you really think it's something going on with your computer, go to Norbiesworld & get him to check things out. It's all free & he's really good. Click on the link below & follow the instructions for free computer help. Download Hijackthis from the links on the site, scan & post the log in the Viruses & Trojans section of his forum.
Norbiesworld
Good luck