I am not aware that it does this.
Which section does it reset this for?

Thanks, Charles ...

Indeed, it does do this, whether I use the file in DOC form (2k3) or DOCX (2k7) or compatibility mode. The book has only two sections, one of 15 pages, and numbered in small Roman numerals (for copyright/dedication/acknowledgements etc), and a much larger one of some 250 pages containing 14 chapters.

This is the second book I have created using Word 2k7, and I noticed the problem last time too. Naturally, it is the second section which is altered by Word.
The original settings are:
"Insert -> Page Numbers -> Page Number Format" as "Start at"- Page 1.
However, at the start of the index creation or replacement, Word repaginates (OK, but its not necessary as the pagination is up-to-date) but repagination is done AFTER altering the above Page Number Format setting to "continuous".

(As Table of Content update does not alter these settings, left to its own devices, Word will mis-number pages in the ToC, as the ToC update does not change the page numbers even if Start At = Page 1, but subsequent indexing will re-number pages.)

Much better behaviour would be to leave the second section page number as set, as this is the convention for the main part of the book i.e. starts at Page 1.

Any suggestions would be appreciated.

Kenneth Spencer