Aapt is a 32bit application. I am running ubuntu 64bit. I needed some additional libraries. First thing I did was update to 13.04 from 12.10. It broke chrome but this should help.
To get aapt working (this fixed my issues with the avd as well) just run these two commands:
sudo apt-get install lib32stdc++6
sudo apt-get install lib32z1
From this post.
Now no more problems.