How to defragmenter window used norton

Hello everybody.

So normally on Wednesdays I open disk defragmenter on Windows 7 to make sure it ran and to see if it's fragmented. But now when I try to open it, I get the message "Disk defragmenter was scheduled using another program. Disk Defragmenter is currently using customized settings created by another program. 
Before you can modify the schedule, you must remove the customized settings." Followed by two buttons: [Remove settings] [Cancel] I can only assume the new NIS update that was installed a few days ago is the reason for this.
 So what does this mean? If I click remove settings, what will happen?

I don't even think I have Norton set to defragment my disk.

Thank's a lot!