Hello David,

The reason I asked is because of the FAQ on this page

Immunization

"Why does Firefox Immunization get undone frequently?
Firefox Immunization works by adding negative permissions to your Firefox profile, which will effectively block elements.

Some registry cleaners are unable to distinguish between positive and negative permissions and will simply remove all permissions from your Firefox profile."

So my next question is, are you using a registry cleaner?

Best regards,
tashi