Thanks to Jason Dishop and Michael Tsang for the tip: Microsoft has posted another post-SP3 hot-fix for Windows NT 4.0. Frankly, looking over the README for this particular fix, I'm not sure I can say that I completely understand the problem. In short, it fixes a problem caused by changes in the way Windows NT handles the SCSI LUN enumeration in Service Pack 3.

You can download the fix from the Microsoft FTP site