This should work....
Code:
Set shell = wscript.CreateObject("Shell.Application")
Shell.MinimizeAll paste that to a text file and then name it whatever.vbs
Create a task that calls the file,, should work.
Let us know if not, it may need some refining on the commands in the Task itself, to call the vbs file properly. I have not used it in 7, but it works when double clicked
I found this somewhere a long time ago.
I have used it before,, but not in a while. I haven't had a need for it in some time.