This is an issue with some client’s computers where AutoCAD LT will open .dwg drawings in a new AutoCAD LT process (window/application) rather than a new tab in the currently open AutoCAD LT.
This occurs when AutoCAD was previously installed on the computer, however was uninstalled. The uninstaller fails to remove the correct registry entries, and .dwg files are associated with the DWG Launcher that is associated with AutoCAD.
- Press Win+R, type “regedit” and hit enter.
- Navigate to Computer/HKEY_CURRENT_USER/SOFTWARE/Classes/.dwg
- Delete the registry key “.dwg”
- Open AutoCAD and when prompted, select “Re-associate file type to AutoCAD this time”. Close AutoCAD.
- Right click a .dwg file, highlight “open with” and click “Choose another app”
- Select “AutoCAD LT” and make certain “Always use this app to open .dwg files” is checked.