When I turn my computer on a blue screen is displayed with white writing every time I start my machine. What can I do?

This is a serious error!! There are hundreds of reasons why this happens. The following are the first steps you should take,,
-Have you installed any new hardware recently? If you have remove it and try to boot again. If the computer boots correctly then you know it is your hardware that is faulty. Take it back to where you bought it and get it replaced.

-Try removing hardware devices in your system. Power down your system and unplug all devices you can such as, Modems, Sound Cards, Scanners, External storage devices etc. Then boot up your system. If computer boots with out blue screening install all the hardware one device at a time, You will now find the device that is causing the problem.

-If the above fails then look at the first numbers on the top left hand side of the screen, they should show something like 0×00000001E simply goto the Microsoft web site and look up the error code, You will then find out how to fix the problem.