I recently updated to 12.04 on my sony vaio VGN-N110G. I've had ubuntu on this laptop since 10.04 and haven't had any real problems. so I restarted my computer today and none of the unity desktop background showed up only the desktop with the files on it.
I brought up the terminal and entered in
unity -replace and restarted it and it came back up fine except that i noticed that my panel only had mail, volume, date/time, and power icons no wireless or bluetooth.
I tried a couple of approaches to try and get it working again i tried nm-applet --sm-disable and it brought up a warning message, i'm not very skilled in code even though i've had ubuntu for four years but in the past versions it wasn't too big a problem