Still Can't Mount Windows Share

[Steve Matzura <sm@noisynotes.com>]

The Windows username is my own name, I have no password set on that
acount. It mounts flawlessly from another Windows machine, but when I
try:

# mount -t cifs //box1/d /mnt/d -o username="Steve
Matzura",password=""

I get:

mount error(121): Remote I/O error
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)

"d" is a directory I created with:

mkdir -p /mnt/d
I know it's something silly, I just can't figure what it might be.
I've tried the system name in uppercase, too; same result.