Anything happen before this happened? Did you try to partition the disk or anythign? This issue is often caused by a partition not being read right on the disk, or a partition being created before the boot partition. This causes the computer hanging at boot, but not displaying the "no boot partition found" messages. Could also be an issue with the drive.
Boot off a Linux live CD and see what type of drives it shows, if you can see the files on the disk OK, and if there are any odd drive letter popping up.