Mobile PC assumes you are only interested in getting from Point A to Point B, and like Ken says it will display only what it thinks may be important at any particular zoom level. For this reason I only use Mobile PC when I need to get to Point B. If you like to see everything, pretty much all the time, then perhaps you would like Microsoft Streets & Trips better. Mobile PC is "smart" in that it keeps you less distracted, which makes it ideal if you are the driver AND the navigator.
Could you post a screenshot, just in case there is a problem?
What you are referring to is another area of the program ( the main actually ) were I confirm MobilePC works pretty well.
This problem shows itself when you do
View Map >> Browse Map >>
The attached picture of South West UK is an example.