Just an FYI, we should all be using our Posting Key for our everyday login and posts.

You should only use the more powerful (and dangerous) activity and owner/master keys for doing things like making transfers and making new keys.

Losing the activity or master key would mean an attacker could empty your account and change all your keys. Loosing your posting key an attacker could only use your account to spam until you reset the Posting Key with your Owner Key.

There is info in the FAQ about this.