To my surprise, stopping the Daz Studio doesn't seem to resolve the SketchBook Pro 2010 hanging problem. In fact, I now start to suspect that it's the "Rotate Canvas" feature that caused the occasion hanging.
So I installed the lastest Release 1 SP2. The version of the original one is:
SketchBook Pro 4.0, 2009 02 23 17 34 (Build 297361)
The new one, on the other hand, is:
SketchBook Pro 4.1.2
2009 12 09 02 03(Build 321671)
Let's see if I still got the problem.