When working on your PC, having Word documents or webpages open means that the pages get loaded into the RAM, to save RAM Windows tends to put various files into your Page File (Like a cache system). Microsoft has left an option to clear out the Pagefile on shutdown off as default, here is the way to switch it on. Take note, this increases shutdown time.

Start Regedit. If you are unfamiliar with regedit please refer to our FAQ on how to get started.
Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\Session Manager\Memory Management
Select ClearPageFileAtShutdown from the list on the right.
Right on it and select Modify.
Change the value to 1 to enable.
Reboot your computer.