Can you tell us what OS version you use and also if you know what update you tried to install?
Can you tell me what OS you are using, Is it Tiger or perhaps Leopard?
That is what I thought, Could you shut down your machine and then power it back up, as soon as you let go of the power button could you then press and hold down the SHIFT key until you see the load icon appear under the Apple logo then let go.
This will force the machine to load into safe boot and when it does just restart like normal and leave the machine to do its thing and apply whatever updates etc it may need.
After it is finished it should respond properly and your files etc should be available.
Let us know if that does not work.
oh my god. my screen saver is gone with all of my documents. help!!
I'm back with a wierd screen saver and set up assistant again
Did you perform the safe boot?
If so did you reboot and alow it to install the updates by itself?