Only some of the brushes work in Painter essentials 6

I have a new Intuos tablet which came with Corel Painter Essentials 6.  From the beginning, I have been unable to use between 40-60% of the brushes.  I am on a Imac and have reinstalled the Wacom driver, reinstalled the painter software, used a test user profile and followed every suggestion of the Corel tech support to no avail.  At best, I have occasionally been able to get the problem brushes to work for a few minutes, but then they quit (usually after trying to change the color.  Is this a Corel issue or a Wacom issue or both?  Any ideas?