Go into BIOS and disable AHCI - Often called SATA compatability mode or the likes - Change it to IDE (most likely what its called), or SATA, NOT RAID OR AHCI .
File not found errors during windows setup usually result of bad RAM.
I don't think your replace battery thingy is an error with Windows 7 - it's simply telling you it has detected its not holding charge that it used to be.
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