If this issue started after February 10, 2015, you may have a Windows update that is causing the issue.
Microsoft Released update KB3013455 in its February update package. This update interacts with the True Type Fonts on Windows computers, making some of them difficult to read. Removing the update corrects the Font display issue.
To remove the update, open Control Panel from your START menu.
Open Programs and Features.
Click on the View installed updates link at the top left of the screen.
Locate "Security Update for Microsoft Windows (KB3013455)".
Select the above update, and click the Uninstall button at the top of the screen
Reboot your computer once the update completes.
You can find more on this issue at the following web address or by doing a Web search for KB3013455: