Well, the monitor size in inches is quite irrelevant. What counts is the monitor resolution in pixels. Most regular (non-widscreen) 19 inchers are 1280x1024, and I would recommend not to exceed that size in any front panel design.
Could it be that the display resolution is set too low in the display properties (possibly by a user with poor eye sight)?
Also check the font size setting in the display properties...appearance. Mske sure it is set to "normal" or the overall size of your panel might change.
For the issue with controls being off the screen, I created a little vi to set the FP origin that can be called every time a user interface screen is called. It is attached.
I make sure all my user interfaces are at 0,0, and thats where this vi sets the origin to, but you can use any coordinates you want. All you have to do is pass in the vi's path using the "Current VI's Path" function.