Are you having issues with you Sidekick LX rebooting at random times? If so you might want to check your battery leads. Make sure that it is seated well when reinstalling it.

The other thing is may be is the Myspace Application. People have reported a myriad of problems with it. Spontaneous reboots being one of them. Remove the application and see if your problem goes away, if not, then it may be time for an exchange.