The problem seems to be that the .png files are not generated bu the latex2html beast.
Running latex2html directly without arguments on the .tex file exported by lyx generated them in a sub dir, and copying these to the main directory made the .html file work. It may be a problem with the version of latex2html I'm using? (Version 2K.1beta (1.47)). Perhaps different arguments :-) apply. -- Stuart MacGregor
