I experienced this same problem. Apparently this is due to the change Sun -> Oracle of VirtualBox.
There's a workaround I found out, that works:
Export The Registry key HKLM\SOFTWARE\Oracle\VirtualBox (with content) to a file.
Open the file with notepad. Replace Oracle with Sun in the registry key ONLY (NOT also in the key entry that point to the path were virtual box was installed!).
Save. Import file with change into registry.
Voila. Now the vmlite xp mode plugin installs!
Reg. file content that did it for me: