Thank you for the reply.
Direct TV is using different HD receivers.
The "normal" HD receiver are only capable of 1080i signals,
Only the so called Direct TV Plus HD DVR are capable of 1080P signals.
Only a receiver HR20 or later will be capable of the 1080P signals.
Also the HDMI cable used for connection needs to be a high speed -HDMI 1.3 cable.
I believe the issue is the Direct TV receiver,not being the "plus" version.
You will need to call them and have the receiver replaced with one capable of the 1080p signals.
In case the receiver is a 1080p receiver,and the cable is a 1.3 HDMI cable, I would still call Direct Tv and have the receiver replaced(may be defective or not have the latest software on it!)
I do not believe the tv is at fault,but if you want to make sure,you can try and hook up a bluray on the tv set.
If the tv will display 1080p from the bluray=the tv is OK.
I hope this will help,
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Thank you so much and have a great day!