Still can't hurt to run mdsched.exe.

That's what my last sentence effectively says.

So it's not "no game starts on a Windows 11 PC" but "50 games do start, 6 do not".
That's a completely different situation to start with.

Try dgVoodoo2 with these games, use the emulation and not passthrough. see what happens.

Also make sure they are installed in a directory where no admin rights are needed for writing. If I recall it correctly, STA writes data into its installation directory and not being able to do so would indeed cause an access error.

And last but not least set Windows compatibility settings for these games to a Windows version from the time when they were released, solving compatibility issues is what these settings are made for. XP-SP3 or Windows 7 usually does the trick. The compatibility settings are what most people keep forgeting about.

OP Knows Better than YOU so STFU for Helping.
But contradicts himself on "only one game has these errors" by showing a list of them.
I am done here.

Mate, this is exactly the kind of detail you needed to offer in your first post. If you flat out told us "other games on other platforms work fine" and then listed exactly which GOG games you were having issues with, maybe mention if you use Galaxy to launch them or not then maybe memory issues wouldn't have been jumped on so hard.

I mean I can understand what happens: you assumed others knew your situation better than you described it. It happens. But letting this go on for so long without explaining this simple bit of detail caused others to waste time chasing shadows. You can imagine how frustrating this is for we forumites: we aren't paid to troubleshoot problems for others, so any time we give you is at the expense of our own free time.

The generic error, like others have said, is really diverse. One possible solution which has been mentioned above:
https://www.gog.com/forum/general/no_game_starts_on_a_new_windows_11_pc/post41
Have you excluded those game folders from your security software? If security software locks out an application because it's suspicious, then it can apparently cause a 0xc0000005 error.

I just stick with 'get the history editions' from the anno series on the ubi store. Fact is, modern age gaming rigs should have nothing to do with those older win 7 type games

Fixed that for you.

I'm not sure you're understanding the point of GoG - which is to provide DRM free versions of games that work on modern systems and modern Operating Systems.

Both M&M IX and Anno 1503 work fine on my 5800x3d, 4070ti and Windows 11 x64. Admittedly, I needed to change compatibility settings for Anno 1503 to XP SP2, 16 bit colour depth and turned off full screen optimisations, but it works fine.

If OP throws in the towel and just pays for a new version from somewhere else, he won't understand or fix the underlying problem that his system clearly has.

Well, why don't you start with asking the right question first before engaging on such fuzzy terms....

I haven't asked a question. I'm assuming you mean "why doesn't OP start with asking the right question", which based on this thread, I agree with as he didn't provide sufficient information in his first post.

Oh, i like your reply!

btw for the OP

I suddenly remembered a couple of silly things

one. i have a msi board, if you install the board there comes something along named naumetic something something to produce real life sound bla bla that actually interferes with quite a few gadgets that help with running those older titles

two.... integer scaling... try it, who knows

https://www.amd.com/en/support/kb/faq/dh2-034