Actually, your drawn lines are locked in place - the rest of the page
elements move around.
Lines (and other objects produced from the FrontPage drawing tool bar, such
as WordArt, shape art, text boxes, etc.) use VML graphics, which utilise
absolute positioning, so they cannot move. VML graphics also have the
disadvantage of only being visible in IE5.5 and later running on Windows
PCs, other browsers will display either nothing at all, or poor quality
down-level .gifs instead.
If the VML is palced inside a table cell, the problems of rendering
absolutely positioned objects from within a table cell become paramount.
Your options are to either:
1) Absolutely position every element in the page, and set up the page so
table cells do not contain AP elements.
2) Use a graphics editor to draw your lines on a larger graphic containing
everything the lines surround.
A link to the page will enable better advise to be given.