My HP 8540p has had Windows 10 installed about 3 times now since after a couple of reboots my computer will stop recognizing the disk. I thought this was a problem with the 320GB disk that came with the computer, so I changed it out with a 1TB Samsung HDD and the problem persists. I have tried changing some BIOS settings to see if that works (toggling UEFI on different installs, enabling/disabling DriveLock, etc.), but to no avail. If anyone has had similar experiences and has gotten out of it, let me know because I need this laptop at least up and running for the school season. I am planning on running a BIOS update when I get home, but I am not sure if that will improve anything. I guess time will tell. Will edit post to add updates.