7-zip SSIS task run with SQL agent gives "This operation requires an interactive window station" error.

I have set up the 7-zip parameters to not require a response, and the process task object to have a "hidden" window.  This is also running with a proxy on the SQL agent.  Is there some other proxy setting, or package or job setting that needs to be done to let this run with the SQL agent?  It works fine running under BIDS.

Thanks,

John