Inaccessible VMs, search not useful

[jarmo]

TL;DR version: Since upgrading from 3.0.x to 4, virtual machines become "inaccessible".

Longer version:
I finally upgraded from 3.0.x (don't remember the exact version) to 4.0.6 and on the same time went from Windows XP to 7.

VirtualBox refuses to find the existing virtual machines. I can add them manually to the list (import the XMLs and drag-and-drop the VDIs to Virtual Media Manager (this only works once)), but this is only a temporary solution because on the next time you run VirtualBox it forgets these and the virtual machines are again "inaccessible".

I have the VDI and XML configuration files for the VMs. What should I do to fix this problem? I tried searching, but the search doesn't ("Sorry but you cannot use search at this time. Please try again in a few minutes."). Apparently the "few minutes" really mean "never".

EDIT: also ignore the "VBox Version" in my profile. I don't know what version I have. The "whatever you get when you download the Windows installer" version.

[mpack]

All you do is copy the complete (and un-messed with) contents of your old "<userdoc>\.VirtualBox" folder tree over to your new <userdoc>.VirtualBox folder tree, overwriting any files which the installation of VBox v4 may have created. Note that the naming convention for your <userdoc> folder changed between XP and Win7, which is why I say <userdoc> rather than "C:\Documents and Settings\Username\.VirtualBox".

VirtualBox v4's default folder structure changed relative to v3, but it is backwards compatible and will use what already exists - if you put it in the right place, and have a bit of common sense about changed paths names, network workgroup names etc.

[jarmo]

That was the first thing I tried and it didn't work.

Guess what? Now it works. Must have been the wrong phase of moon.

Thanks!