Problem: Small squares on screen in some games.

Hallo everyone,

I have recently bought a new system. But I have some problems in games. I wanted to ask you the possible reasons for one of them.
My sistem is:
-Gigabyte P55-ud3r (all drivers up to date. I am waiting for new BIOS to finish its beta status. Then I will update my bios as well)
-Kingston 4gb (2*2) DDR3 1333mhz cl7
-500gb Seagate HDD 7200rpm
-FSP Epsilon 700W
-Intel i5 750
and ATI HD5850

I am using Vista home premium 32bit.

no overclock on anything.
no overheating on anything ( according to HD monitor and CCC results)

I used catalyst 9.10 for a while. After some problems which I guess related to the display drivers (mouse image getting bigger ect.) I changed the drivers to the catalyst 9.11 beta yesterday. I am not sure about the other issues. But one thing is still here.

I uploaded some screenshots because it is hard to explain. You can see the problem easily.

http://img137.imageshack.us/i/65658551.jpg/

http://img294.imageshack.us/i/87735745.jpg/

http://img137.imageshack.us/i/30714515.jpg/

http://img255.imageshack.us/i/23346765.jpg/

As you can see black boxes on the screen in Crysis are very disturbing. The funny thing is that there wasn't this issue before I reached that village after 15min. of gameplay. Then I stated a new game. Everything is perfect again. Then the problems started again when I reacht the village.

On the second screen you can see the squares but they are green now, after a small explosion. But there are black ones on the rifle.

Last screen is from Fallout 3. I experience crashes regularly on that game but it wasn't very good on my previous system as well so it is not the issue. On image you can see the green squares on the smoke/dust effect. I can also see some of them only on clouds sometimes. But they are very slight. You can realize that the squares are only in one area. The rest of the screen is ok.

I also tried Gears of War and Call of Duty 4 but I didn't see anything unusual on both games. I played each of them with full detail for 4 hours. Everything is ok.

The question is what is my problem here? Is it a driver issue or hardware issue? Have any of you guys experienced the same problem?

Thank you very much.

Thank you for your answer.
I uninstalled, driver sweeped and reinstalled my previous update last week. But nothing changed. I installed current one yesterday.

I must be honest with you. I was totally unaware of the DX update thing. I installed my vista last week with my new system and updated. But I didn't install any DX10. And I guess none of the games I installed didn't too.

Where can I learn my current DX10 version?