No picture after start up

My Apple TV was working great when plugged via HD cable into my Samsung LCD.
I have just moved my ATV with Flash to an older LCD using the composite cables (no HD input on the older TV).

I get the apple logo and the intro video but once it has finished, i get no picture.
I get sound still, i can hear the menu clicks but have no picture in the menu.

Any ideas?

Why would i get video at start up but not after the intro has finished?

You may try the fix here:

Thanks for your help.
All sorted.
Had to do a factory reset due to the different TV settings (much lower picture quality) and removing the external hard drive.
Then had tp re_install flash.