I installed a 64bit version of Windows 7 as a virtual machine and when trying to startup, it would hang in a loop of start and restart.  Amongst the loops as the vmware machine would cycle, an error would appear and disappear.  After watching closely I could read enough to see it referred to a bios setting.  That led me to the fix below.

I found out “Virtualization Technology” (VT) must be enabled in the bios settings of my laptop.  VT is an option for Intel CPUs.  This is a requirement VMware implemented for running 64bit virtual machines.  VT is not required for running 32bit virtual machines.

To enable VT, access the Bios Setup Utility on the computer which will host the virtual machine.  Typically, to get to the Bios Setup Utility you press the F1 key when you see the manufactures start up screen when starting or restarting the machine.  When the Bios Setup Utility starts, you will enter Config > CPU.  There you will see the option to Enable VT. [more]

Also, it is documented you must power down the host machine again after enabling VT.  Enabling VT, saving the configuration and continuing with the start up will not enable VT.  It takes and additional cold boot to enable VT.

After the second start, I launched the VMware workstation and powered on the Windows 7 without a problem.