Hello, I've had an issue in which our Exchange cluster would not fail over. Not only did it NOT fail over, it wouldn't fail back. In effect, this rendered our Exchange server unavailalble. Upon working with MSFT support, it was determined that DCOM permissions on both NODES were modified somehow. Resetting the DCOM permissions to their default values (via OLE and COM3 reg keys) resolved this. There were no network changes made for quite some time. Has anyone seen this before? Twice this happened to us. It is quite perplexing- not to mention bloodboiling. Thanx