Sorry to be late in replying; I have only just got the netbook back from the client. I tried hittign F12 really quickly and there was no differrence. However, I have a solution. I thought I had installed Android on a virtual SD card but it turns out it is a real SD card. I took it out and now F12 lets me boot from Windows on the HD or anything else on USB. At last I am free. Thanks for your help.