I don't have a M600, but I do have a Sony Ericsson K818 phone which joystick has stopped working properly.
It's simply a hardware worn-out issue, all electronics experience this and you can't do a lot about it. You can try to replace the component but most of the time it's not worth the effort. Just stick with it and hope to buy a new phone.
Get a Palm web OS based phone instead, you can install pretty much all on it, since it's linux/java/luna based.
i already managed to put IRC client, utorrent to managed the soft on my comp at distance and even a remote desktop controler on my own.
I plan to make Freelancer companion compatible.
MMORPG : Many Men Online Role Playing Girls
WoT: wilwerin - EU server