Computer started up normally, when I clicked on the icon for the mobile internet, the computer froze, and the hour glass stayed there doing nothing. I switched the computer of now asking for a disc (system) How can I get round this with out loosing all my work? Many thanks Graham
More aboutboot disc failure windows
If it asks for a system disc, insert the Windows 7 Installation disc.
Your initial problem sounds like a bad mobile internet driver.
Though if you are worried there are plenty of Linux distros that can run from the cd without installing anything, would give you access to your data to back it up onto a usb stick or dvd etc.