We are sorry for the trouble. Would you mind resetting Illustrator preferences, uninstalling the Creative Cloud using the CC cleaner tool & reinstall it again?
If that doesn't help, would you mind confirming the Illustrator & OS exact version? Also, please confirm when did this start happening? Are there any recent changes made to your system? For example, any antivirus, system updates, plugins, or web extensions installed recently.
I'll be looking forward to your response.