How to troubleshoot OS not found problem?

[kelvin]

as above.

 

[KSoD]

What happend when the problem occured? Any crash logs? Any Error logs? there are many ways just ned to give some more info on what was happening at the time of problem. What programs you were running? What Os are you using? So much information goes into troubleshooting that it isnt just one question it is a series of questions that one must run through to find a answer.