Crazy Problem- Stumped

Ok, so I just bought a new Vizio HD 47" lcd for my home.  I have a standard direct tv receiver hooked up to it.  If the tv is on, The remote for the satelite will work sporadically or not at all.  If I shut off the Vizio tv, I can change channels or hit guide or whatever I want and watch the blue light on the receiver flash as i'm hitting buttons.  Then I turn on the tv and I am right where I should be while hitting the buttons on the remote while the tv was off.  Then I try to use the sattelite remote with the tv on, and it won't work!  Any ideas on something like that??