Error creating control - [text] could not be set on property

I ran into this problem this evening where I had a bunch of custom controls on my page that were complaining at design time that they couldn't set the properties.  After double checking the controls were ok, I started looking around and found this connect issue talking about a similar problem.  For me, doing a build->clean, then build-rebuild all and then existing and restarting Visual Studio fixed the problem.  Read the full details of the connect issue here.