virtualbox.org

Hello,
We have an iMac and upgraded to the latest OS X, Yosemite. After this update, Windows 7 virtualized no longer opens, says that virtualization Intel VT-x is not enabled.
What can we do?
Thank you for your attention.

You may want to check your VB settings to see if VT-x somehow got disabled. If that's not the case then you may want to attach a compressed copy of the latest copy of the VBox.log file for your Windows VM to your reply.