Ok, this partially fixes the problem, though there is a single case that could escape this "protection" if the cell that will be changed, is already selected, then multiple tabs are selected, and then the cell is changed, all cells at that location will also be changed to the resulting data.

I tried to put the same code in the SheetChange event, as I've picked up that when multiple sheets are selected, and data is entered into one of the selected sheets, the other sheets go through the sheetchange event as well, so I thought if I applied the fix you suggested, (Which I was doing something similar in a different event), that the other pages would be deselected and not get updated, however Excel is smarter than that, and still updates the other selected pages, even though they are not selected when it gets to them. :\