Dear Schelprock,
It drove me crazy, too. One server did it, two others didn't.
AC tech suggested using task manager to auto-run a 2-line batch file late at night to stop and restart the service:
net stop "SQL Server (AMAZINGCHARTS)"
net start "SQL Server (AMAZINGCHARTS)"
You can put some pauses in and run it by hand to see if it works for your AC version, but it won't display onscreen when run from task-manager, due to windows-7-and-greater security.
From what AC tech said and the errors that I saw, it looked like a memory-leak problem. A daily stop and start probably resets things before the leak threw away too much memory.
Cheers,
Carl Fogel
