Computer Freezing, Rebooting, and Generally Acting Strange

[MuffinOfFun]

Hello, my computer has been acting up in increasingly odd ways for no apparent reason. Firstly my computer will, seemingly at random freeze up, my monitor will go blank, and it will pop back up, occasionally with an error shown below.

It has also caused my flash player to randomly crash as well. I've done plenty of virus checks, but every time it comes up clean and nothing changes. I'm not sure what to do.

 

[Brett928S2]

Hi

Run a hard drive test in DOS...Hirens cd etc....

All the best Brett

 

[MuffinOfFun]

How would I go about doing that?