I have been building my Android application for 2 years and I have never once had this problem until now.
When I load Eclipse, there is a little progress bar in the bottom right corner of the window which says "Android Library Update." If you click on it, a tab opens up called "Progress" and shows you what is going on.
This has been sitting here not moving for the last 20 minutes. If I attempt to run the project, Eclipse freezes and I have to force quit it. If I do nothing, nothing happens. I am completely stuck and cannot work.
The only thing I can think of which may be relevant is that earlier this morning I was working with no internet connection (I was somewhere else without wifi). I obviously have a connection now (I am writing this post).
If I turn off wifi and launch Eclipse with no internet connection, everything works fine.
Ideas?