Prevent two macros from running at the same time

Hi

I have scripts running in Outlook based on certain rules that are set up. These scripts take the attachment from an arriving email and saves it to a specific folder.

I then have an excel macro that runs every 2 minutes. This macro picks up whether there are any new attachements in the folder. If there is, it opens these files and processes the data onto a 'live update screen' that is mounted on our office wall. This macro normally runs for +- 30 seconds.

With the frequency that the excel macro is running, I am afraid that it might happen where the Excel macro is running when an email arrives and the Outlook scrips then starts processing at the same time.

Question: How can detect whether or not the Excel macro is running to prevent the Outlook script from running at the same time?

Your input will be much appreciated.