Stop Timer Macro From Overwriting Data In All Active Worksheets

I have a worksheet that has macro events attached to command buttons. When a ‘Start’ command button is clicked, a timer begins counting in seconds and displays the value in cell B3 until a ‘Stop’ command button is clicked. The event works flawlessly as long as I don’t open up another workbook (to continue working in Excel).

When the second workbook is open…then time stops working in the workbook where the macro was created…and starts displaying the ‘timer count in seconds’ in the new active workbook--which overwrites/destroys the data in the newly opened workbook. When I go back to the original book that called the macro…it continues counting again.

I need this timer to continue running in the workbook with the command buttons (in the background) while I work on other worksheets in other books. Is there a way to keep the timer running no matter how many other workbooks are opened and prevent it from overwriting whatever sheet is active? This code in the Increment Sub below ‘overwrites’ the contents of cell B3 on whatever sheet is active---and stops the timer in the on the sheet with the ‘Start’ command button.