cannot open my documents, control panel or my computer

Hi,

This began a few days ago but everytime I try to go into control panel, my
computer, my documents or anything else on my start menu the desktop icons
disappear for a fewminutes and then they come back and nothing has opened....
no messages - nothing. Twice when shutting down it said shell con or com
hidden window ending program.
I am not overly tech savvy and after scanning with panda antivirus it turned
up nothing. I am able to use my outlook and internet explorer to access
internet, but cannot access anything else on my computer.

Thanks for any help.