....from all angles.
Not only is nothing happening when keys or mouse are pressed, but also "Internet Explorer is not responding", or "will have to close the troubleshooter" etc. are coming up much too often. Any help appreciated please.
Ivor's suggestion might well do the trick. (It's got me out of trouble often enough!). Otherwise . . .
Try restarting the laptop in Safe Mode (which is usually achieved via pressing F8 during the boot process). Don't panic if you find your screen looks odd; that's just because the video driver won't have loaded.
Then run System Restore (from Start > All Programs > Accessories > System Tools > System Restore) to take the registry back to a date when your laptop was functioning normally.