OraOra wrote:Would creating and deleting a guest VM be able to cause this behaviour?
I'll say No without being authorative
OraOra wrote:I could try and do a restore again to an earlier host image when Seamless Mode worked 100%. Though I have done that plenty of times already.
No point if you have serveral times already
OraOra wrote:Are there some VB logs on C that I could extract from an earlier host OS image?
In your home directory, you should see a .VirtualBox folder. Run one of your VM again and try to go seamless using the RightCtrl + L key combo, then post the VBoxSVC.log inside the folder + the newest VM log and I'll see if there is any correlation.
Doubt we'll see anything new tho...
OraOra wrote:Could it be that the graphics card is failing?
At some point I experienced a flickering of colours on the screen, though when properly reconnecting the cable to the external display that I am using this stopped.
Yes it is possible, but I don't see why it would only affect VirtualBox in this manner. Very unlikely IMO
OraOra wrote:Is there a way to test the graphics card for such behaviour, I mean does the graphics card need have a certain setting or property to be able to support Seamless Mode and this setting or property has gone haywire because the actual hardware is failing?
I don't know...
I have to be honest, I am out of ideas. I am not a big user of the GUI part of VirtualBox so my knowledge tends to be limited here. Hopefully one of the devs will see this topic and help you further.