virtualbox.org

Before, my MacBooPro sported OSX 6.8 and VBox 3.2.14 r75509, and was working VERY well. Support for 2 screens of different size was nearly perfect.
Had to upgrade to Mountain Lion ( 10.8.4) because I needed Safari 6.
As a result my VBox did not work anymore.
This left me no choice but ditching a good working app and to upgrade to VBox 4.2.14 (r86644)
Now Vbox 4.2.14 does not accept my existing VM. It is greyed out in the pick list.

Before upgrading to Mountain Lion, I cloned my disk with the OS 6.8 and the VBox application, the VM being on a separate hard disk. When I use this old situation, the VM proofs to be OK with Windows XP (and MicroStation) working well.

Any hint to get rid of this?
With thanks in advance

I'm not sure what you are asking. VirtualBox v3.x VMs are not very portable, addressing that problem was one of the new features of v4.x. If you simply upgraded VirtualBox then it would see the old VMs and accept them, or you could have used the Export/Import feature. Your problem is undoubtedly because you installed a new host OS which likely destroyed control information related to the existing VMs, and you hadn't exported them to a portable format either.

You say that you built a new VM around a cloned hard disk and that this "proofs to be OK", which leaves me unsure as to what you question now is?

I wanted to make clear that when I keep using the "old" config Mac OSX 6.8 + VBox 3.2.14, my VM is still working and accessible.
I can do this because I cloned the entire hard disk for safety reason, which prove to be useful.
Conclusion : My VM is still in good shape and the onlything to be sorted out is
Mountain Lion and Vbox 4.2.14 getting to work with my existing VM (that dates indeed from the version 3.... era).

You use the word "exported". In the menu bar, there is something that says IMPORT and EXPORT APPLIANCE.
Indeed I did not export anything, as I was not aware of any troubles I might run in.
Whatever "appliance" would mean I will start my "old" configuration with Vbox 3.2.14, hoping I will find the same commands.
If what I "export" in Vbox 3.2.14 can be "imported" or picked up in any way by the new version of Vbox, the problem will be solved.

I'll check out and keep you informed.