Exciting news for the Ultimate 757!

I did uninstall and reinstalled as Administrator.  The message on the little screen in the cockpit states:    "EPR Startup Error!!  Unable to start QA757-1."

You are enabling the gauges in FSX as they pop-up when loading the sim?

When FSX starts and before the first menu page small windows will pop-up with a security warning which will ask if you want to run a gauge or DLL before proceeding. If you don't allow it the add-on won't run properly. That QW757-1 is an activation error generally related to license. From the 757 FAQ forum section;

Your product is not properly activated. Please follow these steps:

1. Launch the Flight1 Purchase Agent and change to the QualityWings Store

2. Open the Library

3. Select the appropriate product

4. Click "License Manager"

5. Select "Refresh Local License"

Ok, perhaps the Steam version doesn't. I had it years ago but found it to be problematic for me. I do have FSX still and it does it with any add-on with gauges or DLL. Again, according to to the developer, your error is related to an activation issue. I would repost your issue in the 757 forum due to the fact they don't do support here. Perhaps they will comment on it. You might try post in the Steam forum. Or you might want to open a ticket with Flight1; maybe it's a license issue at their end.

I don't care for Steam. It's still a 32 bit sim. I have P3d v4 and 5. I have X-Plane 11. I have XP12 but haven't had time to put a dedicated drive in my computer for it, but it looks good. I have MSFS2020. Visuals are fantastic but if you look at Avsim the sim has as many issues as FSX did.