Here's a tip. If you can't deal with problems caused by things installed from extras-devel, then you shouldn't be using that repository. Use the "Deinstall Kernel-Power" menu entry to remove kernel-power, go into the application manager and disable extras-devel, then you can install the version of kernel-power from extras-testing which doesn't have uboot.

Extras-Devel is for things which are in development, they might not be stable and they might mess up your N900, it is a repository for developers and people who want to help test the software, that doesn't mean you can't use it, but you need to be aware of the unstable nature of the software there and be able to deal with any issues the use of such software may cause.

And please, out of courtesy for those reading, spend a bit of time to type properly (people may even be more likely to help you if you do).