I have the same problem with my new dell laptop. http://extremetechsupport.com/forum/laptops-and-monitor-issues/3440-laptop-screen-has-shrunk-please-help.html (Link added by RandyL) The display screen randomly shrinks to 75%. When in Explorer I have to go to View - Zoom - and select - 100% again.
This corrects the issue of small print and white spaces. Plus, on some websites I actually wasn't able to view all the functions because the screen display was shrunk and the scroll bars did not enable a wider viewing size. For example, once I logged in on my company email the LogOut option was on the far right. The screen display suddenly shrunk and I was no long able to view the LogOut option!
It's annoying and inconvenient.
This has happens several times. I noticed that each time occurs right after a black 2-way arrow suddenly appears on the screen. It's really wierd. The icon appears and disappears way too fast for me to click on it. However, if I'm moving the cursor when the icon appears, it shrinks my screen display.
If anyone knows what the black 2-way arrow icon is that would be great.
So sorry for the long reply! Hope this helps.