It could be that there may be something wrong occurring within your AutoCAD 

therefore the best way to resolve this is to perform a reset to default setting for your AutoCAD application. you can do that by following the following steps:

For most versions of AutoCAD from  2012 and later (including AutoCAD-based products), the reset utility can be found in the AutoCAD program group located in the Windows Start Menu:

Start menu > All Programs > Autodesk > AutoCAD(version) > Reset Settings To Default.

The reset utility gives you the option to back-up your settings first. Once the reset is complete, AutoCAD automatically opens and initiates its secondary installer.

For Windows 8 Operating System:

1. Click the Windows button to access the Start Screen.
2. Right-click the bottom of the screen.
3. Click the down arrow to access all the installed apps.
4. In the AutoCAD section, click “Reset Settings to Default.”

For Windows 8.1 Operating System:

1. Click the Windows button to access the Start Screen.
2. Move your cursor down and click the down arrow to access all the installed apps.
3. In the AutoCAD section, click “Reset Settings to Default.”

For Windows 10 Operating System:

1. Click the Windows button to access the Start menu.
2. Click ‘All Apps’
3. Click the down arrow v to expand ‘Autodesk’.
4. Scroll down and click on ‘Reset (version number) Settings To Default’