5.3.0f4 - App with Rift crashes 4 in 5 times

I have an Application that started to crash very often while loading. So I enabled the logs and tried to get some infos from the profiler. But that does not help that much. What I found in the log is:
When the app Crashes the last output is:
Unloading 4 Unused Serialized files (Serialized files now loaded: 0)
(eof)
When the app successfully runs:
Unloading 4 Unused Serialized files (Serialized files now loaded: 0)
UnloadTime: 3.820689 ms
System memory in use before: 156.9...

5.3.0f4 - App with Rift crashes 4 in 5 times