Odd Home Page Reset Message in Internet Explorer

I have a Windows 10 machine which has been disconnected from the internet for several weeks while I wait to pull off files and reinstall the OS. Today I was checking out an XML file which Windows opened with Internet Explorer, when I saw a strange message in a yellow ribbon/banner at the bottom of the IE window:

"Your default home page was reset by your security software"

If I recall correctly, a second tab had opened almost at the same time as the one displaying the file, which showed the standard 'no internet' message in the middle, with the home page reset banner at the bottom.

I tried opening Internet Explorer a couple more times, and got the same odd message as above, but after that, I have not seen the message again, no matter how many times I open Internet Explorer.

My first concern when seeing this was that something on the system (malware/adware?) is trying to change the homepage for Internet Explorer, and something else is blocking it. But I have several anti-malware packages on the system, and none of them are reporting any issues. Additionally, I do not see any similar messages on Edge or Chrome, which were the browsers I was actually using day to day.

I googled the text of the message expecting to see lots of other people reporting it, but there seems to be hardly any mention of it on the internet.

Is anyone familiar with this warning, and can they explain what it means?

I don't think there's a conflict in anti-malware as the combination I have is very common. But just to clarify, if it is my anti-malware that is stepping in to prevent a home page change, that still means that something is trying to change my home page, right?

The thing I was expecting to see on Google is just some mention of this message popping up - since it is apparently a built in Windows function, it seems some of the many Windows users should have encountered it here and there. But in fact I only found two mentions on the whole internet for it..... very odd.

dalchina said:

I'm not aware of a Windows function that protects your home page exposed on the GUI - esp. for Home users.

this is about locking your Home page.
Lock Internet Explorer Home Page in Windows 10/8/7

Your message specifically refers to 'your security software'.

As I said, there used to be quite a few programs that you might install that could change your home page.

To clarify, are you saying you don't think this message is being generated by Windows/Internet Explorer? (It's Pro version btw). If, for example, it was being generated by Malwarebytes, I would have expected it to say 'Malwarebytes has reset your home page' or similar. That the message didn't mention the security software by name was making me think it must be generated by Internet Explorer. Do you think this is not the case?

The other security program that was running in tandem with Malwarebytes was BitDefender (since uninstalled). I can't see any suspicious processes or apps running in the task manager either with or without Internet Explorer open. I recognise all the startup programs, and as for the other apps/programs installed on the machine, the only ones I don't recognise are (I gather) "crapware" programs installed automatically by Windows, such as Bubble Witch, Candy Crush, Keeper, March of Empires, Plex and Autodesk Sketchbook.

Is it likely that a browser hijacker would only try to hijack one (non-default) web browser, but leave the others, including the default browser, untouched?

I'm still puzzled as to why nobody else in Googleland has reported seeing this message if it is indeed something occasionally kicked out by Internet Explorer (albeit possibly with the interference of another program). Seems like the sort of thing that would cause anxiety and provoke some questions on forums.

Can Windows Update ever attempt to change the home page url? The reason I ask is that although nothing was happening with the machine in terms of new programs, I did see a notification of an update being installed (albeit very small/brief) around the same time this was observed.