As of 12/31/2009 the test certificates that shipped with the Windows Mobile SDK expired. However, we’ve gone ahead and generated new certificates that you can drop in to rectify this problem.

If you’re a developer you can put these certificates right into Visual Studio (or sign via command line). If you’re a tester, you can follow these instructions to create a provisioning file for a device, so that you don’t need Visual Studio to push certificates onto test platforms.

Download new certificates here.