OK, so sorry about dredging this up again, but here's something strange...
I can boot up the base installation, or the Dark Avatar expansion like that, but if I try to go for Twilight of the Arnor, all I get is the black screen.
Edit: Never mind... I seem to have fixed the problem by ditching the old folder in my documents for the game... It was the same directory that held the stuff from before... That was before I reformatted the hard drive.
Whatever, everything seems to be good now...