Microsoft Lync Mac crashes on 10.9 Mavericks I have a similar problem like another user had and followed all possible steps including reinstalling and cleaning up Keychain etc before.

The first time I start Lync after a reinstall, I can even see a Menu bar for some seconds. But before any window gets rendered, the Crash Reporter opens.

This is what the error said:


  Microsoft Error Reporting log version: 2.0
  
  Error Signature: Exception: EXC_BAD_ACCESS Date/Time: 2013-10-30
  13:23:14 +0000 Application Name: Microsoft Lync Application Bundle ID:
  com.microsoft.Lync Application Signature: UCCP Application Version:
  14.0.6.130930 Crashed Module Name: libcorecrypto.dylib Crashed Module Version: unknown Crashed Module Offset: 0x0002783a Blame Module Name:
  Microsoft Lync Blame Module Version: 14.0.6.130930 Blame Module
  Offset: 0x002cc862 Application LCID: 1031 Extra app info: Reg=English
  Loc=0x0407 Crashed thread: 0


Any Ideas how to solve this?
Delete

~/Library/Preferences/ByHost/MicrosoftLyncRegistrationDB.xxxx.plist
~/library/preferences/com.microsoft.lync.plist


and check in

~/Library/Preferences/ByHost/


for additional files with lync or Lync in the name (delete them as well). Then restart Lync.