Ok. I have some updates.
The block shadows does not appear when I select "Standard" Print Quality under the Print Preview dialog box.
Shadows appear when I select "High Definition" or "Ultrahigh Definition". Currently I am sending my print output to a Canon Pixma iX4000 on A3+ glossy Canon paper.
All sketchup models with complexity of this drawing level display the shadow problems on the Core i7 PC. Simpler models goes through ok "most" times.
My thoughts are, once the cpu/gpu has successfully sent the high res print output to the printer, video should not be affected on the display. They almost use different paths altogether.
Most times, the block shadows are very stubborn and I could be toggling the texture faces/shadows on/off for like 10 mins before it returns to normal.
I have to do this and hope it reverts back to normal. Off Shadows, switch to hidden lines face texture, then switch to shaded with textures. And repeat after trying shadow on.
Included one of my older models. Just tried and voila. Printed on high definition.
What the model looks like
After sending to printer, with shadows on