The error in general does not usually come up when you start a program, nut rather when already working in it, and you can't exactly do something that will always trigger the error.
The error started to appear only a week ago, and around that time no additional software was installed by the user.
He had just the usual Windows updates.
- did install the Visual C++ redistributable you mentioned: that installed a slighter recent version of the DLL that was already present
- did ALL updates
But that did no help!
We have had the error when trying to opening a log file (TXT) right after notepad started up

But most of the time it happens when working in some application, e.g. when when browsing photo's in Irfanview and trying to rename, after hitting Enter that sets the actual changed file name.
The user did this action countless times before, and never got an error, except when typing iillegal filename

He also gets the error sometimes working in his faithful Excel 2007

You can't really predict when it's gonna happen.
But when we repeat some specific action a lot, it will happen sooner or later.