We have Lync 2013 connected to a Lync 2013 server. Every now and then the Lync Client will sign out and then automatically sign in by itself. Could this be a configuration issue?

All clients or just one user? Sounds like a network connectivity issue.

Some clients. 

Hello Ralph,

Look like issue with network only.

Try to monitor network, many be packet loss will there or network drops.

Best way to open review Lync Log on one of the affected computer and Open EventViewer (Run- type eventvwr)

In Event Viewer - under application event yopu will see some Lync error events (in Red color).

Check the Event and tell us, will help you on the same.

Regards

Balu Ilag [MVP-Lync] 

We have Lync 2013 connected to a Lync 2013 server. Every now and then the Lync Client will sign out and then automatically sign in by itself. Could this be a configuration issue?

This problem can also be related with the trusted certificate chain truncated.

Try the solution in the following link.

http://support.microsoft.com/kb/2464556?wa=wsignin1.0

This forum is focused on Lync client development, so there are few experts here who can help you. I will move your question to the Lync client forum where there are more experts who can help you.

Most likely networking issues, might also be related to Lync Server installation on VM Host

Since you moved the question, please provide a link to the new location.