I would definitely try to do that clean install of Leopard. For 10.5 the two files just became that Extensions.mkext file, which is supposed to rebuild itself automatically as needed or whenever you install/remove a kext file. I'd try running permissions repair from the disk utility to see if that fixes it for you as well.
Just to add, I too have a Titanium DVI that has been unofficially "retired" just due to the accumulated wear. Oh well.
Just to add, I too have a Titanium DVI that has been unofficially "retired" just due to the accumulated wear. Oh well.