I had the same frustration and got a resulution via HP tech support. I don't know why HP can't create a permanant fix for this problem.
The solution is to select the 4x6 size when printing. To do this:
1. Open the Photo and click print.
2. On the printer options menu select show details
3. Next select the printer and seclect "photo on glossy paper-fine"
4. From the last drop down menu select paper handling.
5. click the box that says "scale to paper size"
6. Select 4x6 and print.
This worked for my macbook.