HELP Screen zooms large

[LarryLogic]

I have a stand alone in a customer site where the screen seems to Zoom to 150% on it's own. There is no script or button available for the user to do this.(that I know of) I saw it myself and one specific layout was enlarged and another wasn't. If you exit and re-enter it's fine. I added a button with a script to set zoom level to 100% as a band-aid. It happened again and my button didn't help.

Does anybody know what could cause this?

Larry