Running from sd card... prints skip last few steps

I own a folger tech prusa i3 running ramps1.4. I recently installed an lcd screen, and everything is working right except at the very end of each print the last few lines of solid infill are always skipped. I am using Repetier host 1.06 and slic3r to generate my gcode.
I am not sure if anyone else has run into this problem, but I have not been able to find an existing thread similar to this already. There are steps I will logically take next to solve this, but I am just throwing this out there to see if anyone else has run into (and solved) this problem.
Thank yous.

And what is the firmware you are using?

Marlin runs some G codes immediately but G1s are buffered. To fix this add an M400 after your last movement command to wait for the movement to finish before preceding to codes that turn the motors off or home, for example.

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[www.hydraraptor.blogspot.com]

That sounds about right, and you make my trouble-shooting that much easier. Thank you very much. I am testing it out now, adding M400 to the generated g-code before the homing, fan off, and motors off commands.