You ARE using NT 4.0 server, correct? If not, that's the problem; it cannot run on 2000 or 2003 or NT 4.0 workstation. And did you uninstall both the server and the client software, and did you uninstall any peps and SUs before that?
Then, make sure that the ngensys, ngendist, and ngendesign accounts are NOT already there, otherwise install will fail.
Honestly, with that older version of Express, the best thing probably is reformat and reinstall NT. And make sure that NT is on the D: partition (check all this before you reformat). And with it needing to be on NT 4.0, both unsupported O/S and application software, you might want to consider going to the current version.