Check under the following:
Tools, Options, Print, Update fields.
If this is checked, clear the box.
What appears to be happening is that you have manually formatted the TOC to
how you want it to look like, but you have not modified the TOC styles, so if
this box is checked then Word refreshes the TOC (which is a Field) then send
to the printer.
It is best not to use manual formatting, especially with the TOC.
If you are using 2003, you can have the manual settings forced in to the
Styles but having the cursor on, say, a Heading 1 in the TOC, ensure that the
Style Box (usually top left in toolbar) says TOC1 not Hyperlink (moving
cursor left or right away from the start and end of the line), then using the
Format, Styles and Formatting dialog, scroll down the "Pick" list to TOC1,
right click, Update to match selection. Do this for the other TOC styles
involved.
If you have done major manual formatting this application of style can
initially cause the TOC to go haywire (as you have discribed) but you can now
force the TOC into a format you want and it wont misbeahve again (hopefully).
The above is for 2003, if you are 2007, the descriptions may be different.
Come back if you need any further help.
Check out
http://www.ShaunaKelly.com/word/toc/CreateATOC.html
Hope this helps
DeanH