[unable to slice]

Cura 2.4 on Windows 10. Using the Printrbot Play with heated bed. I've imported the standard Play Getting Started PLA profile from printrbot.com (it's a 15.04-style .ini file). This is the very first time I'm trying 2.4, I've just installed it.

I've tried to load an STL file I made a while ago. That STL works great with 15.04.6 and the Getting Started profile and I've printed it twice with 15.04.6. But on 2.4 I get the error:

 

Unable to slice with the current settings. The following settings have errors: Prime Tower X Position, Initial Layer Height, Raft Base Thickness, Prime Tower Y Position

What's wrong and how can I fix it?

Oh, and maybe I'm blind but I can't seem to find a way to attach the STL and INI files to this post. That's weird. Anyway, here are the files:

https://dl.dropboxusercontent.com/u/29966/3d/pd_base.stl

https://dl.dropboxusercontent.com/u/29966/3d/Play.GettingStarted_PLA.ini

[Edge warping on top of support - is there a way to build a brim on top of support?]

I'm a beginner.

Gear list: Printrbot Play with extended heated bed and glass plate. Cura 15.04.6 on Win10. Standard PLA at 208 C, and the heated bed at 60 C.

This is the STL file:

https://dl.dropboxusercontent.com/u/29966/3d/motor-mount.stl

It's a component for a quadcopter - the motor mount at the end of each arm. I print it with the 3 knobs pointing down, so it needs support. The support settings I used in Cura are:

 

• Everywhere (there's a little horizontal hole in one of the knobs that I thought required internal support)
  
• Linear (as opposed to grid)
  
• default values
  

 

For reasons of strength I use shell/top/bottom thickness of 1.6 mm and fill density of 40% (2x the default values there). The other settings are pretty much default for this printer.

The bottom edges on the main plate are curled up (warped):

Is there a way to tell Cura to build a brim on top of support?

What other techniques I could try to avoid warping on top of support?