Hi Urs,
finally I solved the problem. For any reason I could not identify (maybe it was installing OBJECTFLOW 2.0) the complete content of the respective *.simpleCam file in my document folder was deleted e.g. it was completely empty but the file still existed. The result was that it was not even possible to define new camera positions. After overwriting it with my respective backup-file everything is now working fine again as previously.
Regards,
Rolf