One point you may have overlooked - for a scheduled task to run, it must use a Windows account that logs on with a password. Use Powertoys utility Tweakit available from MS website to automate logging on without having to deal with it (e.g. when restarting or coming out of hibernation). Like I said, I'm only stabbing in the dark to help!
You will also find that the Oztivo instructions for automating the guide updates has been rewritten and is much more straighforward. You will find it here:
MCE < TVGuide < OzTiVo