Hi, if your notebook has been away for awhile guessing either your antivirus/security software may be scanning, or Windows Updates are being installed if you want to check this or give it a day to finish up. By the way have you installed Win10 Anniversary Update yet? Windows might be trying to install this if you don't already have it. Type 'winver' in the search bar to check if you have the latest Win10 version 1607 which Windows will probably be installing for you if you don't have it yet.
Otherwise, if you want to hit alt+ctrl+del and open task manager (details) you can check your disk utilization and maybe identify the program that is keeping your HDD busy, but expect eventually it should stop once it finishes what it's doing.
Hope this helps, but please ask for more suggestions if it doesn't. Thanks.