Setting Z Offset Not Working Right...

[coaxfun]

I'm going to try to be concise, because this one is beyond me.

So I first got the printer, calibrated the z offset, and printed the rook.  When I hit print, it went to the offset, and started printing.

Fast forward to a few prints later, when I go to print, it brings the print surface all the way against the lcd and seizes the motor.  At first, I thought it was just getting to low.  I recalibrated, and the same, again and again.

I had a hunch I knew what it was doing, so I tried a test; here are my steps exactly.

1. loosened the two screws on the print arm.
   
2. clicked home on the manual motion control.
   
3. raised the arm by .1mm until I could move the paper on the lcd.
   
4. did NOT tighten the screws on the print arm.
   
5. set the z offset.
   
6. raised the print arm to 15cm
   
7. selected a file to print to test arm motion.
   

The arm comes all the way down, back to home, does the home test up and down, THEN goes to the offset.

Why did it start doing this all of a sudden?  When printing, shouldn't it only return to the offset?

I tried the above again but set the z offset to 1cm above the lcd surface and same thing.  It goes to home, then goes to the offset.  It makes absolutely no sense.

From looking around the web, it apears I'm not the only one that has experienced this problem.  Is there some solution that just isn't getting shared?