Second time this has happened. New company, new install of ACAD-E 07. Regardless of what project I activate, or what drawing I am on, I cannot use the Previous / Next drawing buttons. Posted with another user november of last year about this issue. Never did see a response. SDI / MDI mode does not change anything. All other project functionality present.
May have found part of the problem. Somehow, the 'command string' value in the tool properties for the next / previous buttons was deleted. I was able to get the buttons to work, but the buttons do not change color based on drawing availability.