Scheduled scan

I have NIS 2009 and cannot get a scheduled scan to work when my desktop is locked. I have tried a scheduled full system scan and a custom scan but neither will run when my desktop is locked. Note that with a locked desktop I am still logged in as the administrator. I have Idle Time Scan set to off in NIS. In scheduled scan properties I have "Run only if logged on" unchecked, in the "Run as" box I have the admin accout and the password entered, "Wake the computer to run this task" is checked. Does anyone have a solution for this?

Thanks.