I have been attempting to install Windows 7 on a Dell optiplex 755 and keep getting the same error message. I have replaced the memory, removed the video card and am using the onboard video card, disconnected all usb devices except for the keyboard. The disc I am using is from Microsoft full version OL windows 7 Pro. I have 2 copies of the disc from Microsoft and have tried both with the same result. I ran a compability check on the machine before beginning the process. The error is as follows:
"Windows cannot install required files. The file may be corrupt or missing. Make sure all files required for installation are available, and restart the installation. Error code 0x80070570.