My recent attempts to build new RPI builds have had issues with XWindows (startx).
startx works OK for the pi user; however, if I build a new user and attempt startx, the Taskbar/xpanel simply flashes gray.
This occurs when I generate a system from Raspian May-5-2015, but it does not when I generate a system from Raspian Sept-09-2014. The xpanel was changed between those dates and the more recent is failing for me.
I have spent hours trying to track down how to fix this problem w/ no luck. Some others have reported this problem. The solution has been to copy ~/.config from /etc, but that hasn’t worked either.
My only solution has been to build systems from the Sep-09-2014 and apt-get upgrade to bring it up to date.
Sep 2015 Update:
Per Lox and Nerdicwalker, below, the problem is the new user is not assigned to the audio group and can be remedied by this
sudo usermod -a -G audio <your_user>