ubuntu 16.04 pixelated screen problem

[uandro]

I am having strange problem on my laptop running ubuntu 16.04. The screen suddenly freezes and what I see is many diamond like symbols on screen. Sometimes it goes to normal after few seconds, and some times it keeps on showing indefinitely. My laptop has no heating problem. I am sure this happens in ubuntu only because when I boot to windows 10 everything works fine. My laptop's graphic card model is "ATI Mobility Radeon HD 5650" and this uses default open source driver provided inside ubuntu since ATI has not provided driver for it for ubuntu 16.04 . I am attaching images. Please help.

[mörgæs]

Does it also happen in a live boot of X/Lubuntu?

[uandro]

No, Ubuntu is installed.

[mörgæs]

It was intended to encourage you to try the live boot.

[VMC]

According to this your chip is fully supported for 16.04.
Look for "REDWOOD".

[uandro]

I do not know what was causing that problem. I have used my pc for two continuous days and I have not seen that problem come again.

[uandro]

I have been using ubuntu 16.04 for 1.5 years but never saw that problem. I think may be that open source driver for my graphic card got buggy update.

[mörgæs]

Good, if you consider the problem solved please mark the thread so.