Well, there are several models under the Otero flag, but I'll make a wild guess and say that the derailleur is a SRAM X-4, right? This one is on the Otero Comp.
The X-4 is a good derailleur for ATB use... that is, for riding on smooth trails and perhaps over rain rutted terrain, but nothing else. If you are exceeding this you are riding harder than what the bike (and the derailleur) is designed for. When the X-4, and the Shimano counterpart Alivio, is subjected to lots of "jiggling around" they will fail. That's just the way it is. If you are riding in rougher terrain then you'll need to think about a better derailleur- perhaps a SRAM X-7 or better. Keep in mind that a Shimano derailleur is not possible unless you swap the shifters too.
Soooo when you are riding keep in mind the design limits of the components and what the manufacturers expectations were when they specced the different Otero models. The Comp is just a beginners model.
