Open a PDF file with acroread (i.e. http://www.wolle-hamburg.de/Bugs/acroread-5.06-r3/sample.pdf) and select "Edit/Find...". Find what: Enter "Something". Click "Find". The result is: No occurrences of: Something were found in the document. Click "OK" and acroread is blown. The same happens using original PDFs from Adobe: http://www.adobe.com/misc/pdfs/tableofcontents.pdf
this is an upstream problem ... at the adobeforums a user reported it happening on Redhat, Mandrake, and Gentoo ... basically it means theres nothing we can really do about it ;) just sit back and wait for a new version to come out that resolves the problem
and we close it for now ...
oh and i filed a bug upstream about it
bugzilla