After googling both broadband.bt.net & bt.openworld addy, it seems as though bt.openworld is a valid internet provider, but broadband.bt.net is un-related to this because googling broadband.bt.net gets you nothing; however, their might be some connection between them. Also, if your ports are being scanned via your friends connection, there is a possibility that your friends is infected with some sort of malware that is using his computer as a zombie computer. Methods to prevent a possible invasion:
1. Keep a fully functional and modern firewall (Sygate is suitable).
2. Use a functioning, updated, and real-time monitoring anti-virus program. Once again, please specify your anti-virus.
3. Use anti-spyware programs. Ad-Aware SE, Spybot S&D, Ewido Anti-Malware, and A-Squared Anti-Malware are all excellent, free programs that will keep your computer clean.
4. Use preventive software. Spyware Blaster, Spyware Guard, and SocketShield are a few preventive programs that are meant to keep infections from entering your computer.
Also, check out Grinler's Prevention post:http://www.bleepingcomputer.com/forums/t/44675/how-did-i-get-infected/
Don't hesistate to post/reply with any comments, questions, etc.!
Edited by Elendil, 01 June 2006 - 07:37 PM.