I had same problem when Update Manager installed kernel-pae! Everything goes back when I purged pae. (My machine has 3 GB memory ram and its incompatible. Check for kernels installed with Synaptic. Good luck!
I clean-installed xubuntu 12.04 two months ago, and everything is running perfect until last night. *I always turned off my machine every night to save electricity, but when I started up my desktop this morning xwindow and/or xfcr4 is not working properly (please see the enclosed screen shoot for an illustration)
* * the titlebars of all the windows (terminal, firefox, any x-applications) are gone
** previously I set the background of the xfce4 panel to be transparent; now it's solid
** previously I set two workspace, but the workspace widget now shows just one, and it does not show any of the x-applications that is currently running (I did check settings-->workspace and its * says that I have two workspace, but under "name of workspace" it only says "1" -- it used to say "1" and "2", I believe)
** I can no longer press-down-alt-and-right-click-mouse to change the size of an existing x-window
** I used noscript in firefox, but when I right click the mouse to adjust permission, I do see the right-click menu but as soon as I move the mouse pointer the right-click menu is gone! *Interesting enough, I don't have this problem in google chrome
** when I click on an x-window that's under another x-window, it no longer pops up to the top.
These are the main issues I've noticed so far; there might be others I have not yet noticed. *You can see the first three issues in the enclosed screen shoot.
I don't remember doing anything unusual last night before I turned off the machine -- it was a clean shutdown (via logout menu), I did check for system update and there was none. * But there were signs of x/xfc4 not working properly -- *I used to have a xdaliclock clock running on the top left hand corner, but a couple of weeks ago that went haywire -- it started showing up literally in the middle of the screen! *It might have happened after a update but I did not keep track of it. *After fiddding with it it, I thought it was an issue with xdaliclock and I let it slided. *Maybe not...
I tried to restart xfce4 but I couldn't figure out how to do that. *I do not mind deleting the current xfce profile/setting and redo that again, but I really can't afford the time to reinstall the machine (project deadline...)
Any suggestions on what's the cause and how to fix it? *Right now the only way I can close an x-window is to ctrl-alt-F1 to console and kill it by hand, and the rest of the system is barely useable (for reasons I outlined above).
I love xubuntu -- I will never go back to unity! -- your help is most appreciative.