The 'msExchBaseClass' class isn't part of the 'auxiliaryClass' for group objects. This may cause Exchange server instability ...

The 'msExchBaseClass' class isn't part of the 'auxiliaryClass' for group objects. This may cause Exchange server instability such as Recipient Update Service processing errors. This issue can be caused by incorrect schema changes.  Click on the link 'get help fixing this issue' in the actions pane located on the right side of the screen for assistance.