The game loses the image but there is sound.

License.
Notebook GX660 specifications:
Processor: Intel Core I7 720QM 1.6 GHz.
RAM: 12 Gb.
Video card: Ati Mobility Radeon HD 5870 1 Gb GDDR5.
System: Windows 8.1
The problem appeared during the Cutscene when we practically escaped from the hospital but the Tank drove into it.
I missed it after about 5 minutes at the moment where Ocelot and I are running away on a horse, the image disappeared again.
Any options what is the problem?
Video card drivers latest available 29 July 2015.