It looks like there is a good chance this issue is related to:
If that link doesn't help, then there are two other potential causes. After opening MATLAB, is it completely frozen? Or can you still interact with its menus? If it is completely frozen, I would check if you have any antivirus software that might be blocking some part of MATLAB. If you are still able to interact with MATLAB after you open it, try following these steps:
- Go to the "File" menu to "Preferences"
- Go to the "General" heading. Click the button "Update Toolbox Path Cache" and press "OK".
- Go to the "File" menu to "Set Path".
- Click on "Default", press "OK" to change, then click "Save" and finally "Close".