When I need to ensure only one copy to run I never used GUID, I always used some combination of project name + my name + current date + customer name/business.

When I need to ensure only one copy to run I never used GUID, I always used some combination of project name + my name + current date + customer name/business. This way is unique and with a personal touch. Also you can make it as long as you want up to MAX_PATH, not the short style that GUID does it.