I startup Ubuntu 12.04 and log into the normal Unity that comes packaged with 12.04. Everything works great, so I start to do some Qt programming with windows like Firefox, Nautilus, and the terminal open.

Sometime later Nautilus folder windows close on it's on with no error message, After many tries of getting the folder windows back open (they keep opening and immediately closing) it may or may not finally open and stay open.

After that other errors start happening such as the window theme remains the same but the window content is drawn very old and basic looking and many of the icons are switched to a simpler alternate theme.

After that tooltips become a solid white and flat window with no text and the scrollbar (and other controls) turn to look like 1990's controls (very flat and old looking).

From there it gets worse to the point where no windows open except the dasher although nothing can be launched from it. Requests to log out or shutdown does nothing either.

Finally I start getting error messages when trying to run a Qt application I might be working on, this is the only error message I explicitly got from all of this and it is

Code:
Gtk-WARNING **: cannot open display: :0
I'm finally left with no choice but switch to terminal 1 via "ctrl + alt + f1" and reboot the system from there.

It's important to note that this doesn't happen all at once but rather over a time of about an hour or two, it does happen repeatedly and I don't know how to fix many Linux errors yet. I've installed several packages on Linux but it's only 2 days old since installation.

Help would be appreciated.