When I connect via USB to my laptop andclick mass storage mode. I get the following message 'Unable to connect via USB. Device storage in use'
My N900 wont mount on my desktop so now I have no way of transfering music anymore. It has worked fine for the last fortnight so don't know what's changed. I cannot use PC suite as I am using a mac. Can anyone help? I have installed any applications on my N900 except for bounce.

Just make sure that no program is accessing your /home/user/MyDocs (shell, file manager, media player)... Then it should be possible. So If really no applications are running it should be definitely be possible to use it as mass storage device.

Another way is to use ssh.

also u can look for debian chroot image if you installed it already, it uses the mc too

On the N900, open a root terminal and type

This will give you a list of programs accessing the MyDocs folder. something like this:
this is acutally an XTerminal program cd'ed into the tmp folder in MyDocs. Note the process-id (3474)

kill the offending program(s):
Try connecting the USB cable again. HTH

Thanks for your help guys. I tried restarting the phone (after you, Emesem, said something was trying to access the mydocs) and I also restarted my Mac and it's working again!!! I'm glad I didn't have to use terminal, it looks complicated. Anyway, I really appreciate everyone who's tried to help me. Thanks

archebyte: Good advice, but one should always try a kill <pid> before a kill -9 <pid> to let the app shut down gracefully if possible.

Thanks for your surgestion, but I've really no idea what debian chroot is...

You guys have lost me!

The kill command from the terminal tells apps to shut down. The pid is short for process id, which archebyte mentioned above, and used to send the shutdown signal to the right process = app. Running kill process-id tells that app to shutdown pretty much the same way as clicking an X in the top corner (think ringing a doorbell and asking the person answering to please leave). kill -9 process-id kills the app immediately, not letting it save open stuff and so on (think smashing open the door and forcefully throwing out the person).

The process id (PID) is like a serial number that uniquely and succinctly identifies an instance of a program that is running. (More than one instance of a program might be running at the same time.)

kill is an application that can be run by simply typing kill in a terminal. kill PID is like asking a troublesome guest with ID # PID to leave.

-9 is an option that modifies the behavior of the application kill. kill -9 PID is like cutting the head off a troublesome guest, possibly making a mess, and increasing risk of harm to yourself.