Last night, I wanted some files off my laptop drive, so I stuck it in an external enclosure and plugged it into my desktop (whilst on). I then turned off the desktop without unplugging my laptop drive and turned it on again today, forgetting to unplug it. I have USB booting enabled, so it tried to boot from the laptop drive and as I was out of the room when it was booting, it entered the recovery partition as the hardware is incompatible. I have done this before, so I just turned off my computer, unplugged the drive, and restarted. Instead of booting from my primary internal drive, it got stuck on the post screen. It detected it, but wouldn't go any further. I then thought that it was still looking for the USB drive, so changed the boot order and removed usb boot, same problem. Removing my primary drive just returned the error "disk boot error, insert boot drive and press enter to continue", so I inserted the primary hard drive (I have it in a hot-swap bay, so it can easily be removed, although being my primary hard drive, not "hot"). After doing so, it kept returning a similar error. I then figured that it was still looking for my laptop drive as a primary boot device, so I cleared CMOS with the jumper and after setting it up again, disabling every other bootable interface except the sata port my primary drive is connected to, and it still just gets stuck on post. I have left it about 10 mins and still get the same problem. It is also hard to enter BIOS or any of the other utilities, as it waits until after post, so I have to either remove all drives or insert the laptop drive in it's enclosure. How can I get my desktop to boot from the primary hard drive again? Inserting the install disk is also hard, because I don't actually have a DVD drive yet, so I installed Windows 7 extended trial through a memory stick from my laptop with a disk drive. I have since deleted it off my memory stick, and my laptop is now in pieces hooked up to my monitor/keyboard/mouse instead of my desktop. It is on it's back and the hard drive bay is open in case I need it again. My BIOS is award with additional features on a Gigabyte GA-H55M-USB3 board. Both drives are Hitachi sata-II drives, one being 3.5" and one being 2.5".