Pierre - Stop jumping up and down.
In Mach3, you can enter values in the DRO's. You do not need VB's and anything else exotic. If you cannot do it, then you have a fault.
Mine does it, Hood's does it, most other people's will do it.
Lets get back to basics. What is your set up. You have downloaded Mach 3. You are using a thinkpad X3 (is that an IBM machine) running Windows XP. What other bits and pieces have you got on the machine - what machine are you trying to run. Why have you got a joystick attached.
What you should be able to do is - on a DRO that is showing program co-ordinates (not machine co-ordinates) - click on the DRO to locate the cursor, Type in the relevant position, Press return - the DRO should have reverted to it's normal colour and your information should be displayed. If you do not press return but go straight to another DRO (or something else) the first DRO will revert to what it was showing before you started.
You seem to be saying that your computer is not doing this - are you sure you have the correct procedure.