When using the hyperref package, you make a block of text “active” when you define a hyper-link (when the user clicks on that text, the reader program will divert to the target of the link).
The hyperref package uses a driver (in the same way as the graphics package does), to determine how to implement all that hyper-stuff.
If you use the driver for dvips output (presumably you want
to distill the resulting PostScript), limitations in the way dvips
deals with the \special commands mean that hyperref
must prevent link anchors from breaking at the end of lines. Other
drivers (notably those for PDFTeX and for dvipdfm) don’t
suffer from this problem.
The problem may occur in a number of different circumstances. For a couple of them, there are work-arounds:
First, if you have an URL which is active (so that clicking on
it will activate your web browser to “go to” the URL). In
this case hyperref employs the url package to
split up the URL (as described in
typesetting URLs), but the
dvips driver then suppresses the breaks. The way out is
the breakurl package, which modifies the \url command
to produce several smaller pieces, between each of which a line break
is permitted. Each group of pieces, that ends up together in one
line, is converted to a single clickable link.
Second, if you have a table of contents, list of figure or tables, or
the like, hyperref will ordinarily make the titles in the
table of contents, or captions in the lists, active. If the title or
caption is long, it will need to break within the table, but the
dvips driver will prevent that. In this case, load
hyperref with the option linktocpage, and only
the page number will be made active.
Otherwise, if you have a lengthy piece of text that you want active, you have at present no simple solution: you have to rewrite your text, or to use a different PDF generation mechanism.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=breaklinks