This is to do with your PC's DPI settings, below details how to amend this.
Below are the steps for changing the DPI setting on Windows 7:
- Right click on a empty area of your desktop and choose Personalize.
- Click on the Display link at the bottom left corner .
- Now you will see this screen.
- To Select a DPI Size . Choose a size that you desire .Here are three choices .
- Smaller - 100% = 96 DPI(Pixels/Dots Per Inch) (which Navigator needs to be set to)
- Medium - 125% = 120 DPI (Pixels/Dots Per Inch);
- Larger - 150% = 144 DPI (Pixels/Dots Per Inch. 
- Click on the Apply button.
- Click on the Log off now button .
- To Set a Custom DPI Size . In the left pane, click on the Set custom text size (DPI) link.
- Click on the drop down arrow and select "Smaller 100%"