Receive location operating service window issue

I’m experiancing odd behaviour with Receive location service window in BizTalk 2006. When I enable service window, the receive location sometimes operates all 24 hours, instead of operating only within the specified service window. This behaviour seems erratic and random.

Not sure if the receive host is being reset during this time which might be causing service window to reset or something else..?  Does anyone else experianced similar issue? Any help/advice is sincerely appreciated.

Thanks,