I'm Wayne And Having A Significant Problem During Shut Down

I have no idea where to post this problem. I am running Win 7. During shutdown, I'm seeing multiple browser windows showing up and having to be closed by the shutdown process. I've run scans and they have shown nothing to be a problem. I was running Norton Security with Backup and noting that the scheduled backups weren't being processed (schedule for every morning at 3 am). I did not connect that problem with what I'm seeing at shutdown. With Norton, I had coded the backup to run only when the computer was idle....now I realize it is "never" at idle with all that must be occurring behind the scenes with all these browser pages. I have a broadband ISP and have a limit of 200GB per month download. Normally I download around 20GB against this limit. In April, that jumped to 137 GB and May jumped 258 GB.....I knew then something was wrong. I notice Task Manager performance "jumping" all over the place. CPU usage will go from 9% to 40% and back down in just seconds. I've run scans and repairs to the registers and cleaned out startup items to those only really needed....but those don't seem to be the problem. I've searched the internet for others having such a problem without success. If ANYONE can help, I'd sure appreciate it. I'm not very technical and I'm very concerned about running some scan program that only makes things worse. Help would be appreciated.