I have a desktop running Windows 8.1 and upon the last set of updates will only boot up to the blue background of the welcome screen.  I she the multi-colored initial screen, then hit the button to start entering my password but the only thing it goes to is a blue screen.  After a couple of minutes it goes back to the multi-colored Windows 8 screen.  How do I fix this? 

Try to update your graphis card driver

Hi,

Have you tried to update the graphics card driver as Nicolas said? And how is the result?

Look forward to receiving your feedback in order to know if you need further help.

This guide should be helpful to you:

Resolving Blue Screen errors in Windows

http://windows.microsoft.com/en-in/windows-8/resolve-windows-blue-screen-errors