My windows 7 dell desktop does not load windows sometimes and ask to press F5 to do the test and after that it does not show a

[sh9000282]

I work in a computer lab and some of computers do not load windows and ask for pre-boot test but when I do it no error will appear.
What is the problem and how can I solve it?

 

[Diganta Das]

I think it's a HDD problem.. It is starting to fail.. Run a HDD test..