The server is all done. One last thing to do – resize that Dell OS partition now that we have the Data partition on a separate 500gb RAID1.

Being an old fashioned person (read: not a Vista user, and new to SBS 2008), I didn’t think to use Disk Management to do the resize. I used Acronis Disk Director. This resulted in the system not booting, with the above error message.

I was at a bit of a loss for what to do. I ran chkdsk from an NTFS bootdisk and this made no difference. Obviously there is no boot.ini any more, and to make matters worse, the Dell supplied SBS 2008 DVDs are non-bootable, so I was a bit stuck.

Whilst waiting the 2hrs for the SBS 2008 DVD ISO to download from, I thought I’d try out a Vista disk and see if that would repair the bootmgr. It did and now all is well.

The problem is apparently caused by the UUID of the partition changing, leaving the bootmgr unable to find it, as per this article.