Leica it seems has isolated the problem with the M9 and various SD cards. A new firmware for the Leica M9 will be released for testing in a few weeks.
The following is from Leica :
STATUS 11.10.2011 (Update of the report from 8.8.2011)
Thanks to the close collaboration with SD card manufacturers, Leica has now managed to rectify the fault by making adjustments to the firmware. To ensure compatibility with as many cards as possible and to ensure that all the related processes remain fault-free and are not compromised, comprehensive testing must be carried out in the development phase. In the coming weeks we will test a beta version of the firmware in practice in cooperation with affected and selected customers.
As soon as the firmware solution is proven in practice, we will name a date for the release of the update.
For background on the compatibility issues, go to our earlier blog post : http://camerawestblog.blogspot.com/2011/08/leica-m9-sd-card-compatibility.html