Originally Posted by: Remco 
- Does NCrunch give you any errors in the Tests Window about your settings failing to load?
No. The errors I get are things like BadImageFormatException when it tries to load a 64 bit dll into a 32 bit process.
Originally Posted by: Remco 
- Are you using the simplified configuration mode? (identified with the checkbox on the configuration window)
- If not, is this setting being stored in your user 'My' config, or in your shared config?
Yes, I am using the simplified configuration mode.
Originally Posted by: Remco 
- Do you have any V2 config files next to this project config file? If so, does deleting them help?
Yes. The v2 files are also set to x64. However, I can't delete them yet because other people (including build servers) are relying on them.
Deleting the V2 file, ensuring the V3 has x64 and re-loading the solution may help. It loaded as x64 at least once, but this problem doesn't happen every time the solution is opened (although once it starts happening, it doesn't stop until fixed) so I can't be completely sure.
Originally Posted by: Remco 
- Can you get this to happen with any project/solution? Or does it affect just the one in particular?
I only have one solution to test it with. It happens with multiple projects in that solution.