If you need to force a safe mode boot on Symantec Endpoint Encryption Full Disk edition (SEE-FD) there are a few options.

Normally, pressing F8 while booting to Windows allows us to enter the Windows Advanced Options menu, but in some cases USB attached keyboards and mice may not respond after authentication to SEE at this time. In this situation, there are two methods to use to force the machine to boot to Safe Mode.

1. Have a Client Administrator login at the pre-Windows authentication prompt and check the box for "Safe Mode Reboot". Registered Users may also be allowed to initiate a Safe Mode Reboot, but this option may be restricted by an administrator.
2. Obtain the latest version of the Recover Utility (v. 8.2.0b) from Technical Support. This option can be used for machines in which the pre-Windows authentication prompt is not enforced.

The recent version of the recover utility contains the Safe Mode Reboot option, and after selecting this option and authenticating with a Client Administrator credential, the machine will reboot and allow you to press F8 to enter Safe Mode.