Hi. I'm taking a look at a colleague's pc which has this problem: the Sata drive (system disk and only disk on the pc) randomly disappears from boot.
You load windows and everything's fine, then once in a while you turn off the pc, turn it back on and the drive has disappeared, the controller doesn't seem to recognize it anymore. So the dreaded "Insert boot device" message appears.
Then after turning off and on and trying a few times, eventually the drive will get recognized again and work just fine.
The computer is an Acer with Mcp61sm-Am motherboard.
I've tried changing bios boot options and such but with no luck. When the drive disappears, it won't even show up in the bios boot menu, by the way.