Did you try to use a bootguard bypass to see if it's going to work in your situation.
http://www.symantec.com/docs/TECH171761
As example:
1) Run pgpwde command from Windows OS to setup a bypass on machine:
pgpwde --add-bypass --disk 0 --count 10 --admin-passphrase "123!" (the passphrase here is 123!)
2) Reboot machine making sure you get access to CD/DVD and try to access the drive to change the password
HTH