"Erik Rijkers" <er(at)xs4all(dot)nl> writes:
> ! pdfTeX error (ext4): \pdfendlink ended up in different nesting level than \pd
> fstartlink.
Known failure mode. That happens whenever the text of a <link> phrase
crosses a page boundary :-(. We've generally worked around it by
tweaking the text so that doesn't happen, but of course we're at risk
again the next time anyone adds/changes text in the vicinity. Can you
identify what linked phrase is causing the problem?
Also, FYI, this is claimed to be fixed in TeX Live 2012:
https://bugzilla.redhat.com/show_bug.cgi?id=619481
so a toolchain upgrade is the long-term answer.
regards, tom lane