Thanks for the help Julian. I think it's important to note that you were on the right track with this.
THe problem is, that if you follow the steps in the above listed article. You will still run into problems with the 10.6.8 update (which also includes all patches from all the previous updates as well). Where you will have this problem booting again.
That article really should be deprecated. I will request to have it expired. Customers are now recommended to upgrade their PGP Desktop release to 10.1.2 Build 9 or newer. See this KB article here which should fix the problem permanently (the above listed KBA is a workaround)
http://www.symantec.com/docs/TECH16322