Problem with changing spaces

[Marc88]

Hi together,

I have the problem that my desktops/spaces are constantly changing. So for instance I assign Spotify to Desktop 6 and Pages to Desktop 4 and a few minutes later Pages is automatically moved to Desktop 2 and Spotify to Desktop 5.

That was never an issue before Mavericks and kind of defies the function of assigning applications to spaces.

Any ideas?

 

[Bruno09]

System Preferences / Mission Control : make sure that the "Automatically rearrange Spaces…" tick box is UNchecked :