Answer by user407749 for "Debug certificate expired" error in Eclipse Android plugins

On Vista, this worked:

1. DOS: del c:\user\dad\.android\debug.keystore

2. ECLIPSE: In Project, Clean the project. Close Eclipse. Re-open Eclipse.

3. ECLIPSE: Start the Emulator. Remove the Application from the emulator.

You are good to go.

I was pretty worried when I say that error, but I fixed it from reading here and playing around for 10 minutes.