Great news Mark!
Anyway, I'm glad I found a way to use AD again. The strange thing is if I load AD beta beside the stable version, I can use another 3 files there without any problems. As a workaround I wanted to load another instance of AD for the time being, but I could not find a straightforward solution to it. Maybe the number of cores is a limiting factor, however I'm almost certain that most of the designers have 4 cores in their workstations. AD 1.5 could handle this flawlessly , so I hope this gets fixed soon.