I have -- well, I had -- a nice setup on my Mac Mini: the internal disk uses rEFIt to select between booting Mac OS X, NetBSD, and FreeBSD (I use NetBSD and FreeBSD for development work at my job), and an external firewire drive, disk1, has several partitions including data partitions for NetBSD and FreeBSD which I share between my Parallels VMs under MacOS and my direct-booted NetBSD and FreeBSD installations. This all worked fine, with the partitioning on the external disk created by Apple's diskutil (to get GPT and MBR tables in sync) and adjusted slightly (partition type and active flag only) by the NetBSD and FreeBSD installers. I could mount the NetBSD and FreeBSD data partitions under Parallels or when directly booted to those OSes from the external disk. Suddenly, after another slight MBR change to disk1 only (still leaving valid, and in-sync per diskutil and Apple command-line fdisk, MBR and GPT tables) on disk1, I get, on Parallels invocation (Desktop 3.0, build 4560): "Virtual machine cannot be started because of the following problem: The Hard Disk 2 is set to use the Boot Camp while Boot Camp is not installed on this computer!" I don't know what this even is supposed to mean, since "Boot Camp" is a package of device drivers for Windows and Parallels happily used the same partitions before, they *are* MBR partitions (a.k.a. "Boot Camp partitions") and they are accessible by MBR-based OSes *and* by OS X. I tried simply erasing the GPT partition table on disk1, so Parallels couldn't possibly think it was out of sync with the MBR table (10.4.7 is fine with HFS+ partitions on MBR-only external drives) and Parallels still throws the same error. The partition name in question, disk1s3, is still a perfectly valid Mac OS X partition and is accessible by Disk Utility or, for example, od or hexdump. I can conclude only that Parallels is doing some kind of "Mommy knows best" sanity checking on raw partitions before deigning to permit users to configure them -- even if those users have to edit the configuration file by hand to use them at all. And Mommy doesn't know best, and it's insanity checking, since it's clearly buggy. This is crazy. Please, tell me there's some way to "persuade" Parallels to stop pretending it's protecting me from myself, and to start attaching my data disks to my virtual machines once more; no adjustment I can make to the MBR or GPT tables seems to make it do so.