Since installing Revit 2011 I notice that using the Wacom Intuos 4 pen to click on the drop-down list in Properties (the one at the top of the new Properties box) the list would not drop down most of the time, but worked OK with a regular mouse.
If anyone else has come across this as a problem, a solution I've just discovered is to, in Wacom tablet properties, set the 'Tip Double Click Distance' to OFF.
No idea why it works, but it seems to