You may have to restart the program in order to get the pallet to start working again. You can also try to go into troubleshooting if available and try to solve the problem as well. Also if you are having a problem with this software you can always try customer service can help you.
Control Panel; Add Programs. Select AutoCAD ;click Change.
Select Reinstall/ Repair; Select Repair; Click Next; follow the prompts to complete the install.
Once the install is complete, reboot the computer.