Since you have no helpful info in your posts, i could only guess, that the kernel-power install failed. You may want to additionally install kernel-power-modules and kernel-power-flasher.
And if you have some sort of multiboot installed you will need the bootimg or multiboot package too.

Thank you for your time.I had kp51r1 and KP settings.No multiboot.Now that you opened my eyes and i thank you for that,I guess something got wrong whit KP cause also the camera failed to start when i open the lens cover after that if i try start flashlight i got device used by other application message.
Also it is possible to film hd whit CSSU stable ?Thanks

Only a working kernel-power setup is necessary, either CSSU or non-CSSU will work.

Thanks again!but in first post in green says that for recording in HD you need to install latest CSSU-T.how can be done whitout CSSU-T?Thanks again!P.S.i have a new and good functioning KP51r1 and CSSU stable!

Yes, you need CSSU-T or CSSU-thumb to be able to record in HD

Thank you very mutch!

Thanks for clarification.
I didn't think at recording

playing videos taking too much time to play on media player, it just keep on loading and loading, tired of this problem.

Every video? Then something plainly is wrong and you will need to be more detailed. Best try to reinstall libraries etc

Some videos? As freemangordon noted, only some 720p vids will play on the n900 with his modified libraries. It is hardware limited and cannot cope with high-end vids. It is also known that a reboot and then a fresh dsp overclock can help.

If your needs extend to top end HD vids, then a new phone is the only way.

i meant to say was "All " videos take much time to load itself, but KMplayer is much faster, hw it could be? and media player is such a slow shitttt