I have a relatively new Compaq (made by HP) computer. I installed RD Tabs, and it would crash as soon as the main screen was displayed. The error complained about the "Verdana" font not supporting Bold. It took some searching, but I found these pages that both describe the issue and have the fix. It worked for me! Apparently this issue is somewhat common on HP computers running Windows 7 64-bit.

http://superuser.com/questions/234566/how-do-i-find-and-activate-missing-fonts-in-windows-7 
http://www.bikingbrian.com/2011/03/06/windows-7-problem-italic-instead-of-regular-text-on-hp-pc/ 

This same issue can also can cause other programs like TurboTax to not start, although TurboTax displays a more obvious message about what the problem is when it happens.