A good source of information when troubleshooting any server issue is the event logs. Lync Server creates a dedicated event log for informational activities, warnings, and errors within the standard Windows Server Event Viewer console. To view this event log, perform the following steps:
1. Click Start.
2. Type eventvwr.msc and click Enter to open the Event Viewer Microsoft Management Console.
3. Expand the Applications and Services Logs folder.
4. Click the Lync Server log.
5. Examine the log for warning or error events, which might provide additional insight into issues.