Reason for Workflow link deactivation

Hi Experts,

We had a production issue some days back where the Workflow event got deactivated and I am trying to find the reason why this happened. I tried to search in previous posts and came across possible reasons but none of this suit our situation.

Is there anyway to find out what went wrong, here are the things I verified so far.

1. Check to see if too many workflow instances are created in a short span

>>> No this did not happen

2. Check if mandatory binding parameter was not passed

>>> There is no possibility for this to happen and it did not occur

3. Check in system logs -SM21 during the time to see if anything out of norm

>>> Nothing, no system issue were found during this time.

Any help is sincerely appreciated.

Thanks,

Ram.