Thanks for the comments, and appreciate the help, robw.
I can’t see where you disable the “pop-ups”. Do you mean General/Show Tips? In any event I am not sure I want to disable the message. I have never done this before but it has never caused a problem before, I have not had such messages.
Note that it is not the opening of the Mixer that is now the issue, it is simply happening during a recording with no intervention.
Irrespective of any pop-up, the key issue is that the recording actually stops.
You note “Usually when I have this problem”… However, I have never had such a problem before, and I have been using Cubase since version 4, updating and upgrading at every point through to 8.05. I have not changed my computer or audio interface in that time. That’s not, of course’ to say that something may have changed in my setup unknown to me - and I assume co-incidental around the time of the C8 upgrade. I update Windows manually regularly, more than once a week. I have checked your points and I see that processor resources are still set to background services and the Power Scheme is still on the same Custom Setting I always have. On checking the list, the recent Windows Updates have been the usual (Security updates, definition updates etc).
Very frustrating as it renders C8 unusable for me at the moment.