This error occurs because the VM’s primary configuration file (the .vbox file) has become empty or corrupted, or because VirtualBox’s global registry (VirtualBox ...

If you're wondering, those empty primary IDE channels were occupied by a spare hard drive (moved to file server) and a CD-ROM drive (broke). The only change I made was upgrading the FastTrak66 driver.

I've been running relatively stable for the last few months. Receive a notification this morning that windows needed to restart for an update. Figure it's something that downloaded in the background ...