I was working on my first Android problem the other day, and ran into a bug with the IDE. I closed it down for the first time since creating and debugging the project, and then immediately restarted it. One of my *.java files had an error on every line. The console displayed a singular error just from opening the project:
"[2010-07-09 14:03:48 - DemoAllFeatures] Project has no default.properties file! Edit the project properties to set one."