Acrobat 8.0 adding numbers to StyleRef fields

I am using Microsoft Word 2000 and Acrobat 8.0 Professional on Windows XP.

I have created Word files that have a StyleRef field in the page header, so that I can show the Heading 1 text in the page header.

There is a section break before each Heading 1.

When I generate the PDF by clicking the Acrobat icon in the Word toolbar, the PDF file has additional numbers added to the header text.

So the first Heading1 text in the page header becomes "1BText of the heading", the second one becomes "2BText of the heading", and so on.

Any ideas why this might be happening? Any setting in Word or Acrobat?