Illustrator crashes, stops responding, or behaves unexpectedly when certain third-party plug-ins or add-ons are installed.
Ensure that all third-party plug-ins you've installed are compatible with the latest release of Illustrator CC. It's possible that your plug-in vendor released an update, while the plug-in version currently installed on your computer is outdated. Check with the vendor whether the plug-in is compatible with the latest release of Illustrator CC and whether you need to upgrade to a newer version.
You may also want to consider removing problematic third-party plug-ins from Illustrator. Consult the documentation for the plug-ins to understand how.