I don't think you'll ever get it to work properly the way you're trying to do it. Totally different hardware when you compare the laptop to the desktop PC.
So, its not surprising that Windows 'spits the dummy' when you install it on the laptop hard drive while connected to the main PC then move it to the laptop.
Perhaps you could try deleting everything from Device Manager before moving the hard drive back to the laptop so Windows detects all the laptop hardware with (hopefully) no conflicts with what was installed on the main PC. You might also have to do a 'repair install' of Windows too.
Some useful info here: http://adamnoffie.blogspot.com/2007/...w-pc-home.html
But, I think you might be out of luck, unfortunately.