My day of complains today 
Anyways, just tried to open a .cpr file via command+O. The finder shows me all files besides the .bak greyed, though “all file types” is chosen. Any one else?
Nope! I’ve opened tons of CPRs no prob.
You must have a filter in Finder?
Weird because it works with 7.5. No filter in the finder. Hm, no idea where I maybe screwed this up. Thanks for clarifying its not a bug. So right click in the finder and open with is now the only way 
…
Ok working again. Why? No idea, one of those things you don´t have to understand
As with all Apple devices, give it 30 minutes, and it just works!
Great, this stupid behave is back. So this is now accompaning the waiting for video device bug. And like this it appears and disappears on random basic. Nice …
Yeah, I’m getting all sorts of weird behaviours that are intermittent like this. I’m trying to find what could be causing this on some Macs, but not on any other, nearly-identical Macs!
Are you running any apps that modify OS X (TotalFinder, A Better Finder, etc)?
No nothing