Computer slows down at same time every night

Every night, at exactly 2:00am my computer starts slowing down, taking forever to open programs, any video playing will begin to skip and get choppy, even switching to AIM from the task bar takes forever. When it happens I look at the taskbar and there appears to be no major programs running, usually just AIM and McAfee. And when I go to current system processes neither are using CPU power, the only thing that has high CPU usage is "System Idle Process" which I don't know what that means. I thought it might be Windows Update but I've disabled it. It is annoying because i usually stay up late and it gets so slow at this exact same time. Resetting the computer seems to work and make it normal but is there a way I can find out why it gets so slow every time at 2:00am?

 

Something is kicking in, maybe it's a virus scan sheduled for that time, or virus updates. Those are my two guesses. Windows Defender is set to do auto scans at 2:00am, as is another virus/malware protection program, but I can't remember which one! If you have Defender installed check it's scheduler. It doesn't have an icon in the system tray by default, you have to go in and change the settings to show the icon, so you may not know that it's running. It's listed in processes as MSAScui.exe.

 

the system idle process is just showing you how much of the CPU is NOT being used, dont worry about that being a high %