Hyperlinks in Excel file suddenly bring up security warning window

Suddenly on starting up my PC today (this hasn't happened, ever, in the past 10 years or more), when I click on a hyperlink in an Excel 2007 document, I get a security message (below) telling me that 'hyperlinks can be harmful' and do I want to proceed? Driving me crazy now, after over an hour of Googling and trying out suggested 'fixes' (in vain).

I have added entries to the registry, added the location (just a local folder) and all subfolders to trusted locations, checked, unchecked various Excel options (all given as solutions to this problem in various forums)....

Irony is, each line in my Excel worksheet contains two hyperlinks: the first is to an internet page, and that still works just fine. The second is, as I say, to a local folder, not unsafe at all, but all those now bring up this message.

Opening the same file in Windows 7 (dual boot) does not bring up the warning, BTW

Anyone know why this is plaguing me all of a sudden (the location clearly wasn't deemed 'unsafe' before today)... and far more importantly, how do I turn this message off once and for all?

Windows 20H2

Thank you!

Thanks Denis. That's one of the pages I trawled through before posting here though: the 'do it myself' options there didn't work for me. I couldn't see (and still don't see) how to download "Microsoft Easy Fix 20189" - I couldn't find a link there to it, or find one that worked by Googling either, and in any case Microsoft 'Easy Fixes' have been discontinued from what I have read? Unless the fix is archived somewhere.

Do you know how to get the Easy Fix?

As I say Denis, "the 'do it myself' options there didn't work for me".. I have tried them twice now :-(

Some I cannot try, as I have, for instance, no registry key "HKEY_CURRENT_USER\Software\Policies\Microsoft\Office"

Thanks...

EDIT: Fixed, I think (see below)

Thanks Denis... I attach a screenshot of the trees I see in RegEdit.. they are different from the ones I read about. I had tried creating a DWord (the same as in your script above) in HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\12.0\Common\
.. there is no 'Security' key there. There is a Security key a bit further down, in 'Excel', but the same DWord created there does not help either. (The PC folders in question appear in the 'Trusted Locations' key, but seems Excel doesn't trust them even so).

The problem seems to be when I create a hyperlink to any local folder (I have tried folders on various drives). The hyperlinks which lead to a page on the internet (same .xlsx document) all work immediately. No problem with the example you gave...

So frustrating after years and years of never seeing this, then suddenly, for no reason I can fathom... PCs, mine anyway, seem to alter settings on their own, with no input from me: just found I had no sound - the joy never ends!! - found that the default speakers had been reset to some other option. Love to know what causes that kind of thing to happen - not due to any input from me!)



- - - Updated - - -

EDIT: OK - last ditch try. I created a new subkey 'Security' within 'Office/12.0/Common', as there wasn't one there already, and then made a new DWORD there - and it seems to have worked! Who knows about tomorrow, but for today the problems looks like it is fixed.

Thanks very much for the help - where did you get the '...Common/Security' key from? I didn't see it mentioned anywhere else.

'then type 'security''..

I failed to read that far! Typical of me I'm afraid, as I get older!!