Book

I get this error message in the status bar of IE6 during book loading:

Line: 127
Char: 32
Error: Object doesn't support this property or method
Code: 0
URL: http://puchemistry.org/course/mod/book/view.php?id=109&chapterid=16

I'm on linux with moodle 1.5.2+ with latest book updated from download page.

Any suggestions?