Internet Question?

[GenuineRisk]

Hey, DTers; do any of you have any idea what might make internet run slow only at a certain time of the day? My internet at home has become mind-bogglingly slow (to the point of being unuseable) at night. During the day it's fine (I'm on it right now) but when I get home from work it's slooooooooow and I can't do anything with it. I have no idea when the speed picks back up; it's still very slow at midnight. I've reset modem, changed Airport channels, disconnected Airport, called the cable company (we have cable modem) and Earthlink. Both of those companies response was "Uhhh.... we don't know..." by the way.

It's not just my internet- one of the other people in the building (or nearby) has an open channel which I hopped on to test and it was just as slow on that one, too.

This started about a week ago and I'm really frustrated.