If your domain is not trusted by Lync, it will show you this warning:
Lync cannot verify that the server is trusted for your sign-in address
To fix it go to your Group Policys and find:
User Configuration/Policies/Administrative Templates/Microsoft Lync 2013/Microsoft Lync Feature/Trusted Domains List
and add your domain “YOURDOMAIN.local“
Create or Edit an gpo.
Go to Computer Configuration -> Administrative Templates -> Windows Components -> Internet Explorer -> Security Features -> Add-on Management.
Enable the Add-on List setting and Press the “Show..” button and then “Add…” button
Write the classid of the addon you want to disable in the “Enter the name of the addon to be added” field and write 0 in the “Value” field.
0 =disable, 1 = enable
Classid of my Java SSV Helper addon is {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} , Brackets must be included,
To find out the class id of an addon in Internet Explorer 9:
Go to Tools menu ->Manage Add-ons
Highlight the addon you want to check and press the More information link in the lower left corner. Classid along with some other information will appear in the popup.