This error is actually a false error, and is caused by GUI caching, more specifically MMC caching. This occurs when a DC (domain controller) that is either unreachable or has changed in some way is still cached by the MMC applet. To fix this issue by removing the cache and basically resetting the MMC applet do this:
Delete this file: "c:\users\<specific user>\appdata\roaming\microsoft\mmc\Exchange Management Console"