Is the magnet that hold the kickstand still there?
Did you check the magnet that AndrewG talk about.its not under the battery cover .open the kickstand and look under the camera.You must have the magnet there or else the phone thinks that the batterycover is off ...
This is the magnet everyone is chattering about, btw. If it's not there (or you just have an indent with nothing in it) then that's your issue. Any small magnet that will fit into the hole will work fine if you need to replace it. Orientation is not important.
@ woody : Thanks for your reply with the screen shot. I have the small magnet and it may have lost it's power i believe. Even when I open my camera shutter the camera app does not seem to be coming. I sent my device to NOKIA to address the issue.
@maxximuscool : Yes, i tried my SD card in other phone it works. I have also one of friend phone who had 2 GB card and when i tried on my N900 it does not see it. So i think it's an H/W issue and I sent it to NOKIA.
NOKIA said they have repaired the phone. But still my phone doesn't see my memory card at all. No messages regarding the memory card also when i do a "dmesg:. Can any experts help me ? Should i ask nokia to give me a new phone ? please help ....