I stopped installing Windows 7 on my customers machines from the dvd and started using usb because of this same problem.
For me what the problem was, was the dvd drive itself. It wasnt reading the disks correctly. So there was times where I would get to the Windows setup and it would give me the same error. Other times Windows would be missing icons or even programs. All because the dvd drive wasnt reading the files correctly and so they where corrupt.
When I made a bootable USB of Windows 7 setup instead, not only does the usb transfer files faster but I can also do scans on the usb if it ever has trouble.
Haven't had the problem since. Also there is a trick that I do every time I reinstall 7 on a store bought computer.
When windows comes pre loaded it is not installed with the cd key on the sticker. Instead it is installed with a OEM key. And there is a cert file installed as well. And in the bios is a SLIC table from the OEM. When Windows looks at all 3 and they match the system is activated. This is why people never need to active new store bought machines.
So when I reinstall those I just skip the cd key part of the setup and I use a tool to install the correct OEM key and cert file. Done, activated and proper.
I never, ever use restore disks. They pre load everything to the way it was when it was bought, which means outdated and loaded with crap. Always do a fresh install
If you like I can give you the link to the tool to make the bootable usb windows 7 setup. And I modified mine to show ever version of Windows to choose from during setup so I only need the one USB drive instead of one for each version of Windows 7
If all other hardware tested fine, then I think you should try USB and see how it goes.
Shane