i cant play age of empires, help me please!

i have played age of empires online since it was available, but since yesterday something weird happens. after 10 minutes of playing AoE online my monitor shuts off and it doesnt go on, it says NO INPUT. but when i turn my computer off and then right back on, my monitor works again. i can do everything and my monitor wont turn off exept for AoE online. my computer is just 2 weeks old and i already did the frame rate and the graphics lower, but it still didnt help. please, can someone help me out? (sorry for the bad english, im from holland)|||Your video card probably has temperature issues.