Lukas
as you have responded to me earlier I am posting a more recdnt response with regards to crashing 7.06 files in 7.5.
- create a backup file in 7.06. This creates a file with an extension as .BAK.
- Next right click on this file and open as Cubase 7.5 eh voila your file now opens in Cubase 7.5. Once you have done this save as normal.
- for double measures on this new file right click and make sure this file opens with 7.5 not 7.06.
NWP note what I had had to go through this afternoon to get to this point.
It may have worked for you but it hasn’t worked for me and a few others.
Can you confirm if version 7.06 should be removed or not as you ( 
) seem to be more in the know! 