Try the latest cleanwipe tool and reinstall it.
Before that read the below
http://www.symantec.com/connect/forums/alleged-pending-system-changes-require-reboot-errors-endpoint-installer
https://www-secure.symantec.com/connect/articles/pending-file-rename-operations
For cleanwipe tool
https://www-secure.symantec.com/connect/forums/how-get-cleanwipe-tool-endpoint-removal
http://www.symantec.com/connect/articles/new-cleanwipe-version-introduced-sep-121-ru2