Screen pixelated

[MoesForum]

Hello, I have strange problem and the resolution settings don't help. There was a device sound then the screen contents went to center of screen small with black around. I feel that when laptop restarted it took this small area and expanded to whole screen making everything stretched and pixelated. The fan is constantly running. I already cleaned it previously.

Dell Studio 1550
Windows 10 x64
ATI mobility Radeon HD 4500 series