It's not a problem related to InDesign, it is one to your printer.
I've only just started using in design, however I was having the same problem. The way I "solved" this was to go to the print menu... file> print. Then go to set up. Under paper size select 5X7 and then under options clicked scale to fit. I don't know if this is the correct way to do this and it did leave a little bit of a border around the pic, but it was good enough to use. Hope this helps
One other thing make sure the orientation is set the same way your document is ie. Portrait, or landscape
These are the settings I used on my printer to try to replicate the problem, and it printed fine -- just the way it was supposed to. Your printer dialog box may look a little different, but should have similar settings as my screen capture below.
If your printer still doesn't print correctly after matching these settings, try drawing a rectangle the same size as the 5 x 7 page, and print again. Let us know if these suggestions solve the issue.