FWIW I had a situation a lot like that reported by @unhammer in #24, but (maybe because I am using a physical disk for the Windows, maybe because it's a different Windows version) I didn't have clear error messages about drivers. However, the fix suggested by @davidstreicher123 in #25 worked: Boot into Windows (in my case, as a main OS), uninstall Guest Additions, go back to Ubuntu (where VB7 is installed) and then boot Windows again as a VM under the new VirtualBox.
FWIW I had a situation a lot like that reported by @unhammer in #24, but (maybe because I am using a physical disk for the Windows, maybe because it's a different Windows version) I didn't have clear error messages about drivers. However, the fix suggested by @davidstreicher123 in #25 worked: Boot into Windows (in my case, as a main OS), uninstall Guest Additions, go back to Ubuntu (where VB7 is installed) and then boot Windows again as a VM under the new VirtualBox.