Hi Paul, a couple of things - first, you are referring to the Min Pixels: setting?
When you say you are inputting values, do you mean by typing in a new value, or by clicking on the up and down arrows?
The range for the Min Pixels: value is 0 to 500 so you should be able to get any value in between.
I don't think I have clearly understood what the problem is - bear with me!
A bit of background:
All the values that use up down controls (or spin buttons, if you prefer) are locked for edit - you should not be able to enter a value in the box. The only way to change one of these values is to click on the up arrow or down arrow. The Min Pixels: setting should go up by one each time you click the up arrow and down by one each time you click the down arrow.
The width/height/cutX/cutY settings are a little different - they are incremented by 4 or decremented by 4 depending on which arrow you click. This is in line with birds instructions that these values should be even and preferably divisible by 4. Also these 4 controls are tied together in that you can't make cutX bigger than the width, or cutY bigger than the height etc.