Have you checked out who the ip/ip's belong to and maybe asked them? I have adsl, and had a very simular problem, I'm not the most technically gifted here and its really a total guess but maybe the same thing.
i have adsl.. cant remember what firewall i was using at the time.. but i was getting icmp pings and ip's trying to connect literally 4 or 5 times a second, it was absolutely killing my firewall cos i was blocking them all ... was lagging me like crazy cos the firewall was going so crazy. I also checked netstat and had a very simular long list of ip's on wait,
I noticed the Ip's were all in the same range and when i did a trace they all lead back to 1 town ( dunno how reliable those trace things r on firewalls ) i did a whois and found out that all the ip's belonged to my isp, I contacted them because i was sure i was being hacked, they wrote back to me asking for my firewall logs, my logs showed in a period of 3 days over 4000 blocked connection attempts a lot of which were high level cos it gave icmp pings a high lvl warning .. everything else was blocked, anyway the long and the short of it is this, I won't try and explain the technical side cos i was confused enough when i read the email..
the isp i was with used dynamic ip's on adsl, and I can't explain how or why, but to designate an ip when a computer was turned on or connected to the net, i would get pinged and connection attempts.. I really cant explain why cos its beyond me, but i ended up leaving the company anyway as their speed was rarely what was advertised.
also a note on that, if its not ur isp, it's always worth contacting the email iot gives on a whois, if they cant at least give you more info they might be able to try and stop it or if it is a hacker do something about it? .. i dunno good luck with finding out whats goin on.