EZ Trak DX bugs?

Hi.
My company purchased old Ez Trak DX 2axis. I have question about bugs, where they told me that in MDI under Z axis I need to write "-0.1" or machine will work incorrectly, and they dont know why. All of they EZ Trak work like that. Softweare version that I have is 5.78. I reinstal it a few times.
What I discoverd is :

1. In CUTCOMP under "Z approach" when I write "-0.1", REPEAT does not work. When I write "0" REPEATE work normaly, but machine does not stop between starting position and runing program.

2. In DR ROW under "Z dr depth" when I write "0" machine does not stop between holes only slows. When I write "-0.1" it runs normaly.

3. When END REPEAT operation is in line after COMP OFF machine twitches between repeating new circle. When I write it in line before COMP OFF it work normaly, but I canot write it under CUTCOMP so I need to COMP OFF first, then go to EDIT and insert line manualy.

Thanks.
Vladimir