I got past the dual boot problem Paul. I downloaded then burned to a dvd and installed from that. The problem is that Linux can't mount the Windows partition because it thinks Windows is hibernating and the disk is in use. I have set Windows to stop rather than hibernate and have disabled "fast start" as has been suggested. I have also run disk clean and check for errors. As an aside, often when I shut down Windows, the computer boots directly into Linux, bypassing the dual boot prompt. After shutting down Linux, it always goes to the dual boot prompt though. This all leads me to believe that the problem is in Windows. Interestingly though, I was able to mount the external backup disk and access its files correctly. I guess that does give me a workaround although not as convenient.