I've downloaded windows 7 b1 from Technet, I didn't burn it, instead, I used Daemon to run setup.exe. It was all OK before Expand File. When it copied all the file, it jumped out a message like this: "Windows cannot install required files. Make sure all files required for installation are available, and restart the installation. Error code: 0x80070061" I've search 0x80070061 through google but nothing found. What should I do???