We had problems with our Dude setup a while ago. One of the symptoms was maps not saving (intermittently), so deleted objects would reappear and newly created objects would not be there next time you restarted the server. Another symptom was history graphs taking a very long time (minutes) to be displayed and sometimes not even displaying at all. After trying many things, such as database vacuums, complete rebuilds of The Dude server, etc we stumbled across the solution. Our Dude system is on an ESX virtual server and the underlying storage system was upgraded. The faster storage resolved all of the issues we were seeing. Depending on your hardware setup, you may be suffering from a similar issue. If this issue has just started for you, perhaps a drive, or drive controller is failing. If this has always been a problem for you, perhaps your storage system is not fast enough?