I think DLA is one of those "packet writing" packages (that allows you to drag-and-drop files to dvd discs (as if it were a "hard drive"). If so, I would recommend uninstalling it under any OS -- they seem to interfere (or cause headaches) for burning your regular DVD-Video discs...
I agree with George on turning it off -- if possible I think I'd try renaming it just in case. Quite a few apps use Sonic licensed software -- some even comes with Vista I think. Dla isn't in the release of Vista I've got, but it isn't the final RTM either.