Last month Microsoft started pushing the upgrade to Windows 10 by including it in the recommended updates. The update is automatically ticked and Windows 10 can be installed without the PC owners consent. I can not understand how Microsoft can get away with this clandestine approach to force users onto the 10 platform. I actually believe 10 to be a very good and fast operating system but it can cause all sorts of issues on older PC's built for Windows 7 and sometimes 8 & 8.1. You should always check your PC's or motherboard manufactures website for 10 compatibility.
Never10 is a great simple little application that prevents the automatic upgrade to windows 10. The small 83kb executable does not need installing you just download and run it. By clicking the button in the centre at the bottom you disable or enable the Windows 10 upgrade on your system.
If you want to remove the Windows 10 icon in you task bar follow these instructions to remove the KB3035583 update.