Invalid Scan Freq. error message on HDTV

I have a SA Explorer 3250HD cable box connected to a Hitachi 32HDT50
Plasma tv.
I don't know if this was the cause or just coincidence but I bumped the cable
remote and the tv screen went black and then displayed the message
"Invalid Scan Freq." Ant A (Basic cable) works but no Y-PbPr.
I have tried:
Hitting all the buttons on the remote,
Resetting the picture format in the cable box
Changed video inputs
etc.
The funny thing is when I put the tv in PIP mode and set Ant A as the main picture and Video1 as the sub picture, it works. But if I switch the pictures,
(Video1 as the Main and AntA as the Sub) , the Video1 signal is there
but very distorted horizontally.
Any suggestions as to what may be the problem?
Thank you,
jabar