This is not strictly RCE, but I am open to suggestions, in case someone has seen this problem.

My host system is a 32 bit windows vista. I am trying to install a guest OS that is x64 bit (either windows XP or vista or linux). Initially it worked seamlessly.
Then I started getting two errors every time I booted the VM:

VM produces an error saying that I need to activate Virtual technology at the BIOS level. Which I did activate, and even updated the BIOS for that very purpose. (http://vmware.com/info?id=152).

The guest OS detects a 32 bit CPU (??? It is x64 quad core Intel CPU) and refuses to boot. Notice that at the moment of install and for a few times, IT DID BOOT.

Suggestions??

Sounds fishy if it did work before. Try double checking if the VM CPU features are indeed enabled (maybe something disabled them). I recently tried 64-bit Win7 on 32bit Vista with VMware and Virtual Box, it ran fine. Guest OS should be getting 64-bit CPU, although it will have virtualization disabled (guest side) to prevent "vm nesting" I guess.

Uhmm. I think I stumbled into the solution.
The problem was the BIOS settings. Even after I had selected VT (virtual technology) enabled, the OS kept reading it as disabled. After power off the computer, disconnect the power. turn on to discharge the condensers, and re-enable the VT option, it started working again. (Mother Board: EVGA NF790i Ultra SLI). Sorry for the interruption, we will continue our normal, scheduled program. . .