Hi
I just had this problem the other day, this works in Guitar Studio 2, it should be in PA9 also.
In console view- right click on the slider- select edit automation data
now you have a window with verticle lines that somehow represent the automation, select the scrub tool and wipe out the lines, that should fix it.
p.s. every track has its own automation data so right click on the same track that you want to edit.