Not yet, I'll do that tomorrow. I'm pretty sure they won't be able to fix it offhanded, they might suggest a replacement of the d-command. But maybe they can refer to sombody at Digi who is willing help us. I contacted Digi's email support on saturday with daily updates, but they're not responding by now.
If I at least knew a workaround, like "repair disk permission and reboot" (I'll try that tomorrow again), it would help us a lot. Another reinstall with 10.5.6 will cost me a lot of time and I can't even be sure it solves the problem...