LBFileDialog is a process that was created to fix issues with thumbnail previewers on some Win64 systems crashing LightBurn.
If you go to the LightBurn program folder and rename or delete LBFileDialog.exe, the program will fall back to using the built-in file dialogs. I’ll have a look and see if I can find any way for the Save As to fail. Are youu just trying to save a project file?