Of course I needed to continue working and so the testing continued as well. I might have found the cause and the solution to the problem.
By default Ubuntu mounts empty optical disks using Nautilus Burner. I immediately click ignore once it pops up and I find it more of a nuisance than anything else. There is an option to disable that option ( System-> Preferences -> Removable Stations), but I hadn't done that yet. When the OPC Failed problem occured again this afternoon the idea popped up to disable the above mentioned option. I have burned two DVD's since, the last one with an altered project name again and it started without a problem. My hypothesis is now the following: while mounting the disk, Nautilus Burner starts up some processes and/or applications that are also being used by K3b at the time. The time frame between me pressing the Ignore button in Nautilus Burner and starting a new burn process in K3b is too short. The conflict results in K3b not being able to start the optimum power calibration. Short is in this case between 10 and 30 seconds (I can click fast). I will continue testing and try to find the processes involved. -- OPC failed https://launchpad.net/bugs/69054 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs