Since were not sure about a few things here's. my best guess.
When you moved files to Ex and deleted same files from Internal something got moved and then deleted from Internal hddthat is causing problem.
Since you don't have OS disc to do repair on Internal hdd here's my idea.
Move all files back to Internal hdd then, Delete all stuff off External.
2. Unplug External and reboot. Should reboot fine. Hopefully. GULP!!!
3. Shut down comepletely Then, Plug in Empty External hdd and reboot.
If it boots up okay then be carefull what you move and delete.
My guess was something got corrupted so that your Internal hdd isn't the dominate hdd in the boot order.
This is the only idea I can come up with as you don't have your OS disc handy to repair Internal hdd this might put those file or files back.
I told ya you weren't gonna like it.
