If you want to prevent a user from running multiple instances of your application on the same computer, you can do so by using a Mutex as shown in the example below.
static void Main()
bool bMutexAcquired = false;
using (Mutex mutex = new Mutex(true, "Unique_Mutex_Name", out bMutexAcquired))
// If the mutex was not acquired, we should not run the app.
if (bMutexAcquired == false)