Check your datastores. Ensure they are still set up and the permisions are ok. Also confirm that the files making up your VM are in the datastore.
I had no problems with the rc1 to rc2 updrade, but when going to rc1, it dropped my datastore, and even though the vms files existed on disk, the vm would not start until I reintroduced the datastore, pointing at the directory containing the files.
I deleted the VM and re-set it up with no luck. The other VMs are working properly.
I booted with a install CD so I could mount the partition and recover the files but the CD could not find a partition or disk to mount.
I checked the configuration and it's pointing to the proper fill. I am out if ideas for the moment.
All I can add is 1) I'm extremely frustrated with the "all new" Server 2.0 and that 2) I'm experiencing the same "No bootable device was detected" for a particular configuration.
Note that I am using Windows XP Professional SP2 (corporate standard for developers), an unsupported platform according to the requirements, so I guess I'm SOL. I'll be going back to Server 1.x or perhaps Virtual Server 2005 since I have IIS installed locally.
For troubleshooting, incase anyone cares, I completely uninstalled, rebooted, installed the latest RC version (changed version number slightly), rebooted, recreated Datastores, recreated Virtual Machine and tried all kinds of different scenarios in the BIOS and VM hardware configuration. No such luck.
A word to the wise: when they say it's unsupported (while also saying they received reports of it working on your unsupported platform), believe them. Save yourself lots of time and frustration and go with another product.