My VMs are located at \Users\Me\VirtualBox VMs\Name. Nowhere in there can I find a .VDI file. I also browsed the Library files for VB (per a suggestion I found on a posting board) with no luck.
When I navigate to the actual VM folders using the path above, I see a Logs folder, a .vbox file, and a .vbox-prev file.
Thanks for your help!!