On startup the icons/buttons aren’t displayed properly and are inactive. The menus work properly as do the tools and tweens. However, to see what is happening the 'Fluid Brush Tool' needs to be pressed between each action/instruction.
Any help would be greatly appreciated.
There was a person with a similar issue some time ago and if I remember correctly the problem went away after updating OS and drivers.
Try to search for the thread if you like or update your OS and video drivers just in case...