Hi, I am having the same problem with the program. I used the directory where the app inventor on my computer was installed to in program files but for some reason it wont take it as tat being where the file is and now i am lost. What I belive you have to do, and I am no expert so please do not quote me on any of this, is put the direct link to where the adb.exe file is, which is where the app inventor was installed to on your computer. Mine I just let it install to the program files. But you must put a direct link to that program, which in my case I am having trouble re-directing the link. I can't figure out how to tell it a new link to look for the adb. So I hope I helped some, and if someone could please help me with my problem that would be great thank you!