I factory restored this machine by pressing [Alt] + F10 several times after powering up I believe this procedure uses the data in the hidden partition to do this.
Right at the begining of the power-up process for just a short while, an "emachine" screen appears plus a choice of using some function keys. As soon as this screen appears (you have to be fast and ready as the time window is very small) press [Alt] + F10 (hold down the Alt key and keep pressing and releasing the F10 key) continuously until a screen comes up giving you the choice to factory restore. Just take the option to restore the operating system.
This process wipes all data from the disk, so you will loose any of your files that might be on the hard disk. It is like a full reinstall and can take about an hour. The machine will shut down and restart several times by itself.
Note, check the bios settings first. There is a "quick boot" and also a "fast boot". Disable both to allow the Alt+F10 keypress to succeed.
When successful, the display shows "starting windows..." in a monospaced font and a text based progress bar, instead of the usual graphical windows start up screen.