OS: Win7 64bit and Standalone License for all products
1. Install Inventor 2011 and ACM 2011 from DVD, - successfully
2. Install all products include ACM 2012 from Product Design Suite Premium USB for the first time and success (because your another post about MDT 2009 install was posted earlier than this ACM 2012 install issue, and in that post you mentioned your PC has ACM 2012 installed already). - Please correct me if my understanding was wrong.
3. Install MDT 2009 but failed with error 1603.
4. Uninstall all 2012 products include ACM 2012
5. Install all products include ACM 2012 again from Product Design Suite Premium USB, but this time you got the message to ask for the disk of ACM. Then you have to cancel the installation.
6. Then you tried to install ACM itself from USB, also got the message to ask for the disk of ACM, then you have to cancel it.
7. You download the EF package of ACM 2012 from web and install it successfully.
Today we tried with the steps already, but I am very sorry that we are not able to reproduce the issue you experienced. We can install MDT 2009 successfully and we can install Inventor 2012/ACM 2012 from the USB successfully as well.
Anyway, it's glad that you have installed ACM 2012 successfully already by downloading the files. Please keep us know if you have other issue meet during installation.