Error occurs upon running android SDK on Eclipse 3.5. Assuming that a lower version of android's SDK was previously installed and tested on the same system.
Actual error I got:
Debug Certificate expired on 9/14/10 2:46 PM Hello World Unknown Android Packaging Problem
This due to expired certificate within the user's directory. To resolve this, kindly remove the said certificate which can be found on:
C:\Documents and Settings\[USER]\.android\
or for Windows 7 and/or Vista
In there remove the file named:
After that, click Project > Clean to rebuild the application. By following this, the issue should be resolve.
Image from http://android.com