OS X 10.4.6 security update overwrites the Windows EFI bootloader.

However, by reblessing the boot partition with the Windows-enabled bootloader, everything is hunky-dory again.

In our opinion, this is not an explicit attempt by Apple to permanently disable Windows dual-booting, but rather, a natural side-effect of applying a comprehensive security update. We believe that the included firmware fix, in particular, may have necessitated overriding the xom.efi bootloader.

For the bleeding-edge crowd that is doing Windows on MacTels, this shouldn't be a biggie.

However, it is unfortunate that the bulletin on the security update makes no mention of this undesired side effect.

We will update this thread as we poke around.

Folks,
Just wanted to stress that reblessing the partition is not really a biggie. It took all of 1 minute for me to do it after the initial reboot with OS X 10.4.6.

Since I kept the original xom.efi in my home folder, all I needed to do was fire up Terminal and issue the command:

And that was it!!! After rebooting, I was back in Windows on MacTel nirvana again.