I ran into this error on a computer recently, and found a sure fire way to fix it. If your iTunes installation says “a network error occurred” and then quotes c:\windows\installer\(file).msi then there is a very easy way to fix this.
Download iTunesSetup.exe and place it on the desktop for ease of locating it.
Download and install 7zip from http://www.7zip.com.
Right click on iTunesSetup.exe and go to ‘7zip’ and then click on “Extract o iTunesSetup\”
Now you’ve got a folder with all the installation files. They are:
Now, move all of those files into the c:\windows\installer\ window you opened at the beginning. Once moved, run the SetupAdmin.exe file. Install will proceed as normal.
PS- this fix is completely original. I did not copy this content from anywhere. I banged my head against the wall for 2.5 hours before it dawned on me what I should do.