Immunization not working with Firefox PE_C_PUBLIC (default)

I have recently updated SPYBOT from v1.6 to V2, and even though its ran "as administrator" immunisation does not work with the section titled "Firefox: PE_C_PUBLIC (default)". I have uploaded a screenshot of the immunisation screen.

My OS is Vista V6.0.6002 (service pack2), I have AVG FRE 2013 running in the background, and the sdame problem occurs is AVG is disabled.

Please have a look into this thread: http://forums.spybot.info/showthread.php?66362-Immunization-failing-Spybot-V-2 if your question is solved by an answer there.
Else you too please provide the informations, requested from the Staff into this thread.

I had to reinstall softyware on my PC, and surprise the problem went away. However the problem is now occuring again. The link did not give any answers, and the reinstallation of software is not a solution either. What is causing this problem with immunization?