Today ,I suddenly find I can't play any mp3 audio file with the default Media Player.When I run the player and select a mp3 file,
It show "Unable to play",But Canola and MPlayer are OK,
why?

Back to the future... I had 3 n900 (somehow now dead or unchargeable) having this issue for reasons I still can't identify.
I reflashed a new second hand n900 a few days ago and I re-enjoyed mediaplayer working for all my files again. But since yesterday, it is broken, again, and I can't figure out why.
The most frustrating thing is that I know I did nothing by myself to make this issue happen simply because I was sleeping between the moment it was working and the moment it was broken.

As far as I can tell, the problem is really similar to this *closed* bug:
https://bugs.maemo.org/show_bug.cgi?id=6823

I've tried a lot of things (restarting trackerd, killing mafw-*, reboots, run it with strace, etc.) without success. When trying to play any audio/video file, it still shows this error message (translated from french) "impossible to process operation", even trying to change the mediaplayer volume triggers this error.

If anybody here is still using his n900 and its mediaplayer, please give some feedback!

Note: openmediaplayer suffers of the same problems, an was working good when mediaplayer was working too.

--
PS: my firmware is 20.2010.36-2

Do you get the DSP MMU fault in dmesg as well?

What happens if you try playing it with gst-launch (see http://linux.die.net/man/1/gst-launch-0.10 and look for playbin or playbin2)?

No, I don't have any thing related to (grep -i) "dsp", "dspmmu" nor "fault" in dmesg.

I don't have this command and apt-cache | aptitude search doesn't help to locate its package. (And unfortunately, I don't have apt-file at hands on my n900!).
Which package is it from?

Edit: I have to mention that mplayer works "well" (it can be interrupted at times, when receiving sms , etc. but is almost OK).

Thank you by the way!

OK, I've located gst-launch asking apt-file on my Debian laptop. It is in gstreamer-tools package.

My intuition is that this mediaplayer issue is related to something stupid like an orphan lock file or an erroneous communication with the underneath decoding libraries. Is this latest guess the track you want me to explore, i.e., trying gstreamer as a stand alone player?

You do realize that you posted your n900 media player problem in the n800 subforum right?
I am just illuminating this so that it doesn't confuse n800 owners...
and to let you know you will get more n900 users looking at the problem in the n900 subforum than here...

Oh! thank you, I didn't realize!