Check all of the cables and connections in the actual cable lines. It could be that your cable lines in your house/apt are old and aren't transfering a strong enough signal. You can buy a signal booster to bump it up. Also if you have any splitters you could be cutting your signal down a lot... Try testing it right where the cable comes into the house/apt and see if the problem persists...

Good choice switching to comcast... Their customer service SUCKS but once you get the internet working solid it is AWESOME .

By the way nice alizee (sp) avatar...!