This morning, while addressing Christmas cards, I had several applications running. At some point during the session, my desktop environment (Unity 3D) became unreponsive for several minutes at a time. My trackpad pointer would move, I could click on applications or Dash Home in Launcher, could attempt to minimize an application but no response at all until a minute or two passed.

I had GRAMPS, Rhythmbox and Firefox (maybe 2 tabs open) running when this occurred. I suppose Update Manager could have run in the background, but I had already manually updated earlier.

Would anyone have any ideas where I could look to attempt to diagnose this? I didn't see anything in Log File Viewer. Googlubuntu didn't seem to have anything definite that I could find.