So, in my infinite wisdom, I decided to repartition one of the drives in my late-2011 15" Macbook Pro to install Windows 8.
240GB SSD - Win7 and OSX boot/OS partitions, plus new FAT partition
750GB - Win7 and OSX data partitions
NO INTERNAL DVD DRIVE - I removed it and installed the SSD in its place long ago. I have an external DVD drive, and a 32GB USB stick, but of course the MBP doesn't want to boot from either of those. I really, really don't want to have to open this thing up and reinstall the superdrive.
Up until now, I've been happily running Win7 and Lion in parallel via rEFIt. Today, I used the OSX Disk Utility to resize the OSX boot partition to make room for Win8.
Now, Win7 won't boot. I was getting a "BOOTMGR missing" error. I went into the rEFIt shell, and it asked if it could update the MBR. Genius that I am, I said, "Sure!" and now, instead of the BOOTMGR error, I get a "non-system disk" error.