Somehow, the Application Event log count ended up to 18,446,744,073,709,551,499. This causes MMC snap-in to fail when I want to see the event using Event Viewer, giving a System.OverflowException (Value was either too large or too small for an Int64.). Any thoughts, or should I just clear the log?
Maybe it helps if you activate the option to override old eventlogs when the log is full. This should prevent you from loosing the newest log entries when reaching the limit.
To activate navigate to your eventlog and go to their settings. There you find an option to override old entries if the log is full.