Check in firewall and My network connections and see if the network mentioned there is yours. Also check in PC and Home network tools and see if the PCs mentioned in the MY Network list are all yours. Also in navigation open security history and check around the time these events occurred.
Under 'my network connections' I see my wireless network plus 3 others. These are displayed as 3 groups of IP addresses each starting with the xxx.xxx numbers which correspond to my LAN port IP. They are displayed as 'home network' and 'wired'. Not sure what these are.
Under 'my network' I can see my devices, plus there are a number of other devices displayed as 'offline' which state 'unknown device'. I am assuming these are devices of guests which have visited, or would they usually display device type?. The lists are different on both machines.
In security history there is not much - about 20-30 'blocked connections' around the time of the event that I remember. I have looked these up on utrace and they all seem to correspond to known companies or 'content delivery networks'.
I believe this is because the Command Prompt must be run in Administrator mode or in "Elevated Mode" to accomplish such commands. This is necessary even if you are logged in as an Administrator.
Here's a Tutorial on how to run it in that mode and please note at the bottom of that first post another Tutorial about creating a shortcut to an Elevated Command Prompt.
I find it invaluable.
Sorry I missed the bit about command prompts opening spontaneously and just read the bit about them closing. That usually is because something that needs authority to do so, is updating in the background. Are there any clues in your Event Viewer at around the same time as that appearance?
Also check in your Control Panel > Programs and Features to see what McAfee programs are registered there. If you see Security Scan Plus (or even Norton Security Scan) uninstall those. I've known those, which often come as optional downloads with Adobe products, cause this phenomenon.
But usually it's some program that needs a higher authority to do something and calls up the window momentarily in the process.
As a precaution I would run a few anti-malware scans. Some suggestions in the last link in my signature below.
Many thanks for your help.
I am not sure of the sort of thing in the event viewer, but over that time in the Windows log there seem to have been many actions by MSI Installer including uninstalling and reinstalling HP support assistant. Would that be the sort of thing?
It's probably something to do with that then. I'm not familiar with HP software but I recall on a Dell computer getting similar issues and in the end I got rid of every vestige of their software and ended up with a machine that was not only popup-free but ran far more smoothly too. I'm wondering if HP support might know more.
Thanks for all your help. Seems like I was being paranoid from a security perspective.
PS regarding my reply number 2, should I be seeing these additional 3 'wired' networks under 'my networks' in McAfee?