Known issue. Just run LiveUpdate to update your definitions.
Similar thread here:
https://www-secure.symantec.com/connect/forums/ie11-crashing-related-sep-update-symantec-endpoint-protection-12
Symantec Security Response blog about it here:
https://www-secure.symantec.com/connect/blogs/corrupt-ips-definition-package-impacted-internet-explorer-11