No idle time quick scan

I have been using NIS for the last 5 years and I have never faced any problem till I installed NIS 2012 ver 19.1.1.3. First problem I faced was reputation scan which was rectified by Norton technician during on line support by taking control of my PC. Now for the last few days I am facing new problem that is no idle time quick scans, I have left the PC idle for hours no scan. Manually I can start quick scan and it runs fine,also till now I have never been able to schedule a full system scan I want to scan every Monday at 1900 hrs and I leave PC idle at that time but no scan. Today live updates failed to complete.

 My PC spec are windows 7 home premium, ram 3.0GB, Intel core 2 duo.