Re: Suddenly being subscribed to threads...
Please go to "My Settings".
In the menu panel on the left side, click on "Edit Options" under "Settings & Options".
In the middle of the page under "Messaging & Notification", the second box is titled "Default Thread Subscription Mode". Click on the little downward pointing arrow for the drop down menu and choose "do not subscribe". Then scroll all the way down to the bottom of the page and click on the "Save Changes" button.
That should stop the subscriptions, going forward.
For current subscriptions, look again into the menu panel on the left side. About the fifth one down is "Subscribed Threads". From there you can edit individual subscriptions or empty entire folders of all subscriptions.