I had a similiar problem in the past. With DirecTV internet, you will need to get a Dynamic IP address, only availabe for the buisness users. It sucks big time also, as they charged me an additional $40.00 / month to have It. Needless to say that was awhile back, and I'm back on Dial up, But that's the reason. Check If you can get a Dynamic Ip through there service.
stephen
PS welcome to the boards.