I also had the same problem on Wed. 3-28-2012. I called cox and told them this started happening after the cox Upgrade ( forced reboot) and not a Update ( no reboot required), so they sent a Technitian out and determined I needed a new Modem. That was installed and tests were ran on my PC and all was good until I rebooted. The problem came back. I then contacted my Tech friend in Florida that is a certified Hardware, Software, & Internet Tech. We used Teamviewer to try to resolve the problem on Friday morning 3-30-2012 we found the culpret. If you turn off the McAfee "Real - Time Scanning" the internet using IE9 or Firefox, now works super fast with no errors and it now downloads without lock-ups of freezes.
I am now running McAfee with all other functions but Real-Time Scanning without issues, even after reboot with it left off. If I turn it on it starts up the problem again.
I am calling Cox support to inform them of this and hope I don't have to remove McAfee ( as I have been comfortable with it since McAfee became Cox McAfee) and have to switch to Microsoft Security Essentials.