Hello, Gianni,
After looking at the specification of your system, I am somewhat confused about your GFX configuration. As a rule of thumb Intel Iris Pro Graphics is not a sufficiently powerful GPU to work in DaVinci Resolve.
nVidia GeForce GT 750M might work OK.
Would you be able go to DaVinci Resolve Preferences I/O – GPU tab and see which of the GPUs is detected when you experiencing this issues?
Are you able to play other media?