On XP SP3, 12GB drive, du quits at (i.e., just before) my directory 
"C:\Program Files\".

Command is just "du" given at root directory: "C:\>du{Enter}"

If the last directory before Program Files is "C:\oracle\" then the last 
lines listed are like:

12345 ./oracle/foo
23456 ./oracle
34567 .

If I rename "oracle" to "Zoracle", then the last lines from du are like:

1234 ./MyProjects/bar
2345 ./MyProjects
3456 .

in other words, du lists directories up to, and not including, my Program 
Files directory (in alphabetical order).

Is there any debug switch to enable, short of recompilation from source 
with debug printfs?

C:\Program Files\gnu\gnuwin32>du --v
du (GNU coreutils) 5.3.0
Written by Torbjorn Granlund, David MacKenzie, Paul Eggert, and Jim 
Meyering.

Peter F. Klammer, P.E. 
Staff Engineer, Design
Denver Product Development 
 
HID Global Corporation
10385 Westmoor Drive, Suite 300
Westminster, Colorado 80021
303 404 6740 (Office)
303 915 2673 (Mobile/Personal)
303 404 6888 (Fax)
PKlammer@HIDglobal.com
www.HIDglobal.com