Seen a few references to this. My tablet is doing it too.
If I power on with a uSD card installed, the BIOS Splash screen is displayed correctly but then the top half of the screen (in landscape)/right half of the screen (in portrait) just displays as lines stretching from the middle of the screen to the edge. The bottom/left half of the screen is fine.
Some have suggested it is related to Intel graphics drivers as generic VGA drivers don’t do it (but are the wrong resolution) apparently.
Pretty fundamental failure though… I get the feeling users are beta-testing this tablet.