In reply to Greenbanks:
Are you using Windows 8? Are you using it on a laptop?
It removes the pointer if you don't have a mouse or equivalent attached, expecting you to use touchscreen functionality instead (which you may not actually have).
If it's doing this while you still have some other mouse, touchpad, or equivalent device attached, it probably means it can't 'see' that other device - which might be faulty, or have been disabled.
Have you, or another user, maybe disabled a laptop touchpad, perhaps by mistake, or because it was annoying when you leant on it and you didn't need it anyway due to having a remote mouse? There might be a keyboard shortcut to re-enable it - start by looking at the Function keys at the top.