Hi guys,
don't know how, BUT GOT CAMERA WORKING AGAIN!

I've done so many uninstallations that I'm not sure what made it work again. But finally I didn't have to reflash my N900. I think that the latest apps I removed were FrontView900, FlashLight and mbarcode and its several plugins. Then I rebooted once more again.
Of course I managed to purge catblock app but I guess that it was not the cause of the problem (but it was the cause of many other ones in my phone).

Definitively, it has nothing to do, for the moment, with CSSU, power-kernel or pr-fremantle apps. I'm now reinstalling mbarcode and frontview900. It seems to work correctly. Now I go with FCamera. I'll tell you later.