by Dan Marsden.
If you've never installed crot/urkund/compilatio/moss/programming plagiarism plugins in the plagiarism directory then the eventhandlers won't be the issue. You will either have an issue with your Turnitin configuration settings - try resaving that page and make sure you have a succesful notification of connection to Turnitin and if that works fine re-check that your cron process is not getting stuck somewhere.
then try creating a new assignment in Moodle, enable turnitin within that assignment and then login as a student, submit a file, make sure cron is running every 15min or so - and then in an hour or more re-check the asssignment to see if the file has been sent and a report has been generated.