Some of you probably found this thread due to the unstable versions of Android-Tools pushed (exclusively) since the stable 22.3 version.This causes a 'hang' in the emulator on the "Android Animation / Splash Screen" in Intel API's pre Version 19, and a "floating point exception" for Intel API-19.The ARM versions still work, though more slowly on Intel machines using acceleration.
To answer the questions of "how to find the older versions not listed in the GUI" - or present in the current xml which feeds it (https://dl-ssl.google.com/android/repository/repository-8.xml), in the comments above, I have no idea how they can be located (please enlighten me).
Fortunately, someone reporting the bug did post a direct link to the Linux and Windows versions of the stable 22.3 version in this thread:
https://code.google.com/p/android/issues/detail?id=66786... which are:
These also exist in unofficial locations on the web, should those get pulled down, along with the now-gone references to them.
After extracting that archive, you will have the "Tools" folder you need to replace the broken one, as per Ariel Iriarte's instructions above (though I renamed the existing 'Tools' folder something involving the letter 'f' - days into this problem).
In order to prevent this problem from re-occuring, do NOT count on the built-in method in Eclipse / Android-SDK to revert to a previous installation, nor for the older-versions of any file provided by Google to be available At All, Ever, in the future.Backup your entire 'android-sdks' tree prior to installing anything.