Quick tip from lockergnome.com
It’s frustrating, you did everything right. Yet after running a few new programs, you find that your brand new install of Ubuntu 10.04 is not playing ball when you go to shut it down.
What gives? Let me ask you this — did you run Open Office with the quick starter applet enabled from within the software? If so, this is the issue. To fix the problem, you only need disable the Open Office autostart.
The way I did it was to open up Writer, then goto Tools>Options>OpenOffice.org>Memory. Uncheck the quickstarter box. That’s all there is to it. And now you can turn off the Ubuntu computer without any further problems.