COMPUTER "BLINKING"

I love to play the games here, but I have a problem.

I bought a Dell PC for a while back. I love the improvement from my ancient last one, but still this one do something strange when I play these games. Note it's just when playing these games, and it makes me a little frustrated. Please if anyone can help me I'd love that!

The problem is that when playing the screen "blinks". Sorry if the english is bad :) I don't know what is wrong. The blinking is regular. It makes my eyes hurt. Any suggestions?

My little santawish :)

Thank you all creators for wonderful games! Your effort is much appreciated :)