Micro station v8 tentative button assignments and snapping

When mapping my colleague's button assignments as Data=left button, Reset = right button, Tentative = 4 and command = 3  (which is what we all have it set to with no problems).

An error occurs  when snapping on the screen; you have to position the digitising mouse to the very far left just to be able to snap to something.

However if we remap the buttons so that Data =Left Reset = 4 and Tentative =right ..it works. This is not the best set up for my colleague to work with.

We have checked the wintab.ini file and it matches mine. we have checked the partition set up.

Does any one have any more ideas please ?

Thank you