tabular
environment (or something
similar) was used.
This arrangement can provoke problems, most commonly with deep section
nesting or very large page numbers: the numbers in question just don’t
fit in the space allowed for them in the class.
A separate answer discusses
re-designing the tables
and those techniques can be employed to make the numbers fit.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=tocloftwrong