Word 2003: Indentation suddenly not working

In Tools->Bullets and Numbering->Outline Numbered, I selected the graphic with
....1)
.........a)
.................i)
While in Word, I hit Enter and the first indent and
...1)............came up. I typed "Test" and it became
...1) Test........... Good. Then I hit Enter, and saw
...2)................... Also good. I then hit Tab, and the cursor indented, but left the "2)........." where it was - not good.
...2).........x<-tab here. It should have showed
..............a).........Typing "Test2" caused
....2).......Test2...Wrong. It should have been
...............a) Test2

in other words, with a tab on line 2, Word displayed
.......1) Test
.......2)............Test2
but line 2 should have displayed as
.......1) Test
.................a) Test2

In the past, hitting tab would cause Word to indent to the next level. (Hitting <shift>Tab would cause a return to the previous level.) I could not find any setting in Word 2003 to fix this, so I did a reinstall. It still does it. Can anyone please help me out here?