Vista - windows explorer crashes after running idle

Hi,

I am fustrated with vista. If walk away from my computer for about an hour
and come back explorer crashes; the start menu looks like a sheet of glass so
I can't see anything to press and if I try to open my documents or any other
folder, they also appear as a sheet of translucent glass. The taskbar also
get screwed up - sometime it also looks like glass or the items in it get
shift right under the start button. I can still open applications if they're
on the desktop.

I actually have to remember where buttons are on the start menu or on the
taskbar if I want to access the respected application. I can't even print
screen to show anyone this cause for some reason it won't work - when I go to
paste on any suitable application the paste button is deactivated.

After a longer period and I loose internet connection. I'm left with 2
options; restart my computer or wait for a window to pop saying "explorer has
encounterd a problem and will now close", followed by "explorer is
restarting".

Why is this happening and how can I fix this?