My fight with Amazon Unbox - Alpha Blog - alpha.cnet.com:
I left work after that and rebooted my laptop at home. That's when the real trouble began. I noticed that the Amazon player had launched itself. Annoying. I looked in the program for a preference to stop it from launching itself, and there was none. Typical. So I went to msconfig and unchecked Amazon Unbox so that it would definitely not launch itself at start-up. When I rebooted, it was no longer there. However, my firewall warned me that a Windows service (ADVWindowsClientService.exe) was trying to connect to the Net. I clicked More Info in the firewall alert and found it was Amazon Unbox. Downright offensive. It still was launching a Net-connection process that even msconfig apparently couldn't stop. Forget it. That's not the behavior of good software. I went to uninstall it.
After the Install Shield launched and I chose uninstall, I got a login screen for my Amazon account. I just wanted to uninstall it. I shouldn't have to log in to my account to do that. So I canceled the login, and the uninstall failed. I tried that three times, and it failed each time. Finally I gave up and logged in and the uninstall finished.
So, in summary, to be allowed the privilege of purchasing a video that I can't burn to DVD and can't watch on my iPod, I have to allow a program to hijack my start-up and force me to login to uninstall it? No way. Sorry, Amazon. I love a lot of what you do, but I will absolutely not recommend this service. Try again.