Are you facing the problem only with PDF files?
what is the version of ewebeditpro ..are you using VF5.1?since the version is changed,if you are using the same config.xml in previous version,it may throw some strange errors in 671 in various cases.check the ektron forum,you will definitely get the solution.check the new developer guide too.Let me know if you are facing some other issues with VF
"http://devnet.interwoven.com/forums_vb/showthread.php?t=24091&forumid=13 "
"http://devnet.interwoven.com/forums_vb/showthread.php?t=24091&forumid=13 " discusses the same / similar issue!