I bought this about 15~20 months ago as a refurbished unit. It had Windows XP Professional pre-installed and a product key code to validate it but no CD. While performing maintenance on my hard drive (defragging, etc) the Compress option got checked and I can no longer boot the system. I know there is a hidden "recovery" feature to reinstall the Windows OS but I do not have the instructions on how to activate it and have been unable to find an online manual that explains how to access the Install feature.