If you have similar situation and have no idea what to do, here is solution.
You probably have Hyper-V enabled as part of your Windows configuration. Hyper-V is the successor of Microsoft Virtual PC and is probably enabled by default, during Windows installation or some manual user activity. However, after you uncheck/disable this Windows Feature and reboot your Windows machine, you should be able to install 64-bit guest versions within your favorite virtualization platform.
So, with combination Windows Key + q or from Control Panel, search for Turn Windows Features on or off. After you open this windows, scroll until you see option Hyper-V, uncheck it and reboot your machine. When system is back, open your virtualizion platform and you should be able to install 64-bit guest operation systems as well.
Hope this help you and save your time. If you found this article helpful, please share it with others and support my work that way. All your comments, feedback and suggestion are more then welcome.