I'm facing a strange behaviour in a Win7 x64 host after upgrading VBox to the latest 5.x branch (5.08 first and then 5.10).
All VMs seem to work well, but most of them (various Windows guests) do not close properly anymore.
If I regularly "turn off" the VM the guest OS seems to shut down correctly but the VM manager shows "interrupted" instead of the usual "off".
If I exit the VM by saving its state the saving dialog appears as usual, together with the % indicator, but the VM ends up in "interrupted" state as well. I noticed that when the VM windows closes the "saved" tag actually appears for a moment in VM manager under the VM name but it gets immediately substituted by the "interrupted" one.
In both cases, when started up again the VMs seem to boot normally.
Any suggestions about some possible reasons for such a behaviour?