Totally dis-integrate the meeting room from your regular office. Make the meeting rooms into small cubicle meeting rooms for various capacity, and put a secretary and office boy. If anyone need to use the meeting room then it should be booked/reserved for duration and once it is over then every one should leave the meeting room and it is locked. The meeting partitions can be removed easily for AGM or for a larger capacity meeting and put it back as before. Each office staff will function from their own office or cubicle, and when a meeting has to be conducted with clients then they use meeting room with prior booking/reservation and time availability. This will end the issue, as what the person do in his own cubicle or room is seldom ignored as far as he does his given work and show result.