I'll try to start from the beginning, if there is one....
I have XP Pro on a Primary partition on an IDE device; all my subsuquent Vista builds have gone on Logical partitions on this physical drive.
Up to build 5381, Vista has worked pretty well with the BCD stores and bcdedit and bootloader menu. I decided that since Beta 2 was imminent, I would free up some space, so I killed builds 5308(17/60),5342, and 5365, but kept 5381. I forgot to make changes with VBPro and I had an initial booting problem with 5381, but that was fixed with WinRE.
I installed Vista Beta 2 a few days ago and was pretty "wowed" by it all, seemingly very stable (Except for the 3 IE7 crashes today.....) and all, but then I noticed when I rebooted that I was missing the 5381 selection, but somehow that came back, but it was unbootable. I then downloaded, installed and ran the VBPro program and received errors, as well as 5381 being missing again from the choices of OS's. I'll let the images speak for themselves: This 1st image was taken from XP, the rest are from Vista Beta 2
Notice the 5381 entry is located at an "UNKOWN" drive
This is the error I get opening VBPRo in Vista and XP
And this is the other error I get in VBPro; notice 5381 is missing
I ran WinRE from DVD to fix the 5381 booting error and the following images show what happened to the HDD's regarding the \boot directory.... it's gone now from all installations.
The ONLY way to switch back and forth between OS's (Vista/XP) now is to use VBPro and set one as default and reboot; I still do not get the boot menu selection, as the default OS just boots directly.
NOTE: I cannot add a Vista entry via VBPro, that selection is greyed out in XP and in Vista