I have had my N900 for a week it was a present but has now developed an intermittent fault. When attaching headphones Shure or my Sony ones even the nokia's default ones don't (show headset icon) I have tried all the headsets on my E75 and they all work fine.

I have done some system hunting and checked the output of dmesg and it is being detected see below. Every time I connect and disconnect I see the below. Even though the system shows connected sound comes out the speaker and not the headphones.

[4821.719726] headphone (GPIO 177) is now connected
[4823.336883] headphone (GPIO 177) is now disconnected

can anyone help with this issue?

I have been having the same problem..
Not sure whats the reason about it but I just unplug it and plug it back in.. and the icon shows up..

It is also happening for example playing music through the speaker and then I attach headphones, the headphones are ignored and music still comes out the speaker.

My unit is still under warranty so may take it in for repair as this is not the way it should be working.