When turning on my XPS 8500 I got "No bootable device available", also you can see that SATA 0 (HDD) is installed. When running an ePSA diagnostics, it shows N/A for the HDD, but in the system configuration it shows that my Seagate Barracuda 2TB has only 4GB (probably volume X:). I used the windows CD to boot and use the troubleshoot to Refresh my computer, and got "The driver where Windows is installed is locked. Unlock the drive and try again". Then in cmd using diskpart, list disk, there is no online disk to fix. Already been a couple of days trying without results. Does anyone can help me resolve this? I don't want to reinstall Windows and lose all my files. Help will be very appreciated. Thanks.