Disabling the change of desktop///??

hello,
i have a problem, i have about 60 laptops that go out with employees every day. i the problem is that i have the my computer,network neighborhood and my documents hiden, well not hidden i merely replaced the icon so it looks like the background of the windows destop “solid blue”> now i have a couple of employees that have figured out how to get to my computer and get into things they shouldn’t be gettin into.
all help is welcome, thanks again
computer analyst,
koury