Windows 7 wants to re-activate if I switch host OS

[washirv]

Kind of similar to topic "Which changes trigger reactivation in a Windows guest?", but very specific case.

I run OSX on one partition, Windows 7 under Boot Camp in another. I run WinXP and Win7 guests from Virtualbox from either host OS, depending which I booted into that day. Before last week there was no issue. I'm not sure whether a VB or Windows update might be responsible for this.

The XP VM still behaves well. Recently the Win7 guest always wants to reactivate Windows when I switch between OSX and Win7 as host OS. The guest itself does not change, and yes, its product key is different from that of the Win7 host OS.

I dig that the change in host OS might well trigger a perceived "hardware" change which fools Windows into thinking it must reactivate. Question is -- any way to prevent this?

[mpack]

To avoid Win7 reactivation it must be the same VM-UUID on both hosts. The easiest way I know to achieve that after the fact would be to first unregister the existing VM ("Remove" within the GUI, but keep files), then manually edit the .vbox file, changing the uuid field in the "<Machine uuid=" line to match that of the other VM. You can then use Machine|Add to add the VM back to the GUI.

Also, you should copy (not clone) the VDI file when copying it between VMs. If you have previously used the GUI cloning feature then you may need to hack the media registry in the vbox file so that both hosts agree on the hard disk UUID.

All other VM settings should be as identical as possible on the two hosts, particularly on features visible to the VM. RAM size, MAC address etc should all match.

Snapshots would be a bad idea in this scenario.