Unable to open C6.5 projects in C7

Projects made with Cubase 6.5 on OS-X 10.6.8 are not able to open in Cubase 7 OS-X 10.8.2.
Cubase 7 crashes when I want to open the projects. First I thought that it had something to do with the used plug ins (soft synths) but when I erased the softsynth and saved it again in Cubase 6.5 it was still not able to open in cubase 7. It’s also not possible to load this projects in Cubase 6.5 on OS X 10.8.2 . So it has probably something to do with OS-X .
please fix this asap!