How To Check If Macro Is Scheduled Or Not

I have a button that runs a macro every 5 seconds.

I have another button to stop the loop.

Problem happens if a user hits the stop button when the sequence is not running - they get an error.

Here's my code for button 1 (start) and 2 (stop):

Code:
Sub Process_Emails_and_Backup_Auto()
Application.Run "Process_All_Emails_In_The_Inbox"
runtime1 = Now + TimeValue("00:00:05")
Application.OnTime runtime1, "Process_Emails_and_Backup_Auto"
End Sub
Sub StopProcessing()
Application.OnTime runtime1, "Process_Emails_and_Backup_Auto", , False
End Sub

Is there a way for button 2 - the StopProcessing macro - to run a test like If process is scheduled then run this code - if not then don't?