No changes that I am aware of on the computer. Rebuilt my users profile and still unable to log in. I tired and I also can't log in. We both can log into other computers and LYNC will work.  I think something had to corrupt a file on the computer--but I have searched for several days and have been unable to find a fix. Any help appreciated.

The first thing I'd check is that your workstation fully trusts the certificate the server is using.  Are you using an internal certificate authority on the Lync server? 

Hi Dawn7665,

 

The first thing, I would like to confirm that do you mean the Lync client crashed ?

If this is not the case, skip it and check the certificate as Anthony stated.

In addition, please try to turn off the system Firewall and Anti-Virus program which might block the traffic.

Also please make sure the network is available.

 

Best regards,

Eric