artroland, I've found that if I try to "directly select anything within the viewport" when the Spot Render tool is selected/depressed D/S won't let me select. If I select the Translate tool (for example),which de-selects the Spot Render tool I can then select anything in the viewport. It seems to do with having the Spot Render tool selected when trying to select an item in the viewport. Atleast in my case. Hope this helps :-)