Norton Keychain Password

I'm running Max OSX 10.6.7.  Comcast security recommended I install Norton Antivirus for Mac, which I did via their website.

 

In my Keychain there is now a Symantec Keychain which is locked.  My Mac password does not open it, nor does my Comcast password.  I did not set a password.  Where did this one come from and how do I find out what it is?  Thanks.