photosmart c4780 is only printing half way when I print on 4x6 photo paper.

[cmoulding]

I've having problems on my HP Photosmart C4780. When I load a 4x6 inch photo paper it pulls the paper in, starts printing, pushed the paper out, but has only printed half of my photo. 

It looks as if it starts printing before it reaches the paper becasue the back has ink lines on it and when comparing it with what prints, to what should print, the photo looks like it starts printing at the middle and is right up against the leading edge of the photo paper.

There are no error messages at all.

I'm using windows 7

the printer is connected via wireless

I have no other problems printing 81/2X11 or from any programs.

Any help would be great.

[ome]

i have same on photosmart 5510 wireless notebook windows 7 added a small length of blank paper to entry of photopaper and it works but why does this happen

[ome]

i have same with photosmart 5510