I am using Lync in my office laptop , past few months I was not able to use Lync calls and was getting the exactly above subject line as a error so I contacted help desk , reinstalled Lync, they tried many things but unfortunately they were not able to fix it.
I also started to Google but no luck after trying many suggested things
Finally found the fix and here it is..,
Step 1 Completely Close Lync
Right Click the Lync Icon near by Time on Task bar then Exit.
Kill any communicator.exe in Task manager
Step 2 Right Click Lync Icon and go to properties –> Compatibility Mode
Step 3 Uncheck the “ Run this Program in Compatibility mode for “
Note : In my case it was checked to “Windows XP (Service Pack 3)”
Sorry I could not attach screenshots due to my office laptop.