Have you tried unplugging your cable modem and then plugging it back in.....I've been told to do that by the cable guy when it acts strange.
I have unplugged the cable box let the info download both for the TV and the broadband when both are up and running we get 2 light on the box. Only one light for the TV is showing the other is flashing so I think I have either a download problem from the cable provider or the box is playing up.
We had to do that too when we had DSL, now we have a dish. I don't think the dish is any faster than DSL, but hubby thinks so.