Ran into an error as I was trying to log into Lync the fix goes as
1. Quit out of Microsoft Lync 2. Go to /Users/username/Library/Keychains 3. Remove the OC_KeyContainer__username@company.com file from /Users/username/Library/Keychains. 4. Launch Microsoft Lync 5. On relaunch, the prompt no longer appeared.
Not the most elegant solution, but I'm logged in now.