You'll find some pdf files are created deliberately to be un-copyable.
There is a freeware or two that tries to get round that, but I don't
know any links.
The author of InfoRapid, which uses the program pdf2text to search
collections of pdf files, informs me that defeating the copy
protection feature of pdf files is a simple matter, but that the
author of pdf2text has chosen to respect the "do not copy" flag on
such files. He does suggest there there's a patch for the program that
will override this limitation.
I'd like to find this patch myself, as I've got a collection of about
two hundred copy protected pdf files I need to search.
The irony is that the producer of these files is itself looking for
some means to allow such global searches, having put these files out
on their website and on freely distributable CD-ROMs, but can't bring
itself to remove the copy protection.
Achim
axethetax