LBFileDialog is the child application that LightBurn launches to open files so that if a badly written preview tool crashes, it doesn’t take LightBurn with it.
Try this: In C:\Program Files\LightBurn look for ‘LBFileDialog.exe’ and rename it (just add .bak to the name). That will cause LightBurn to fall back to the internal dialog that doesn’t provide the crash protection.
I’d be very curious to know why this is failing though - It’s a very simply application. Can you go to Help > Generate Support Data, then open a Notepad, click ‘Paste’, save that to a file, and email it to support@lightburnsoftware.com with a link to this thread? I have heard of one, maybe two other people who’ve had an issue with this, and never once been able to re-create it.