Logging process stop

I’ve got the following problem. I started to use WinGate 3 Pro as a proxy server of our network couple months ago. Last Saturnday, when I wanted to make a month Internet usage statistics, I unexpectedly discovered that logging process for all activeWinGate services was terminated 07/09/2000.
The last event of every active service log file contained the same action “Service Stopped”. This circumstance confused me because WinGate is still online and logging is on for every active service. I want to know why logging process stopped and why Wingate doesn’t append new records in log files.