Download and run Sysinternals' Process Explorer and see which process is using the most memory
Also, enable the VirusTotal check in Process Explorer by clicking on Options > VirusTotal.com > Check VirusTotal.com
It's also possible this is a virtual memory paging file (known as the pagefile) issue.
See this article on how to set it up...
Failing that, your hard drive may be running low on disk space, in which case you should run Disk Cleanup, and download and run the free tool WinDirStat to see where and what is using the most disk space.
Edited by jwoods301, 26 June 2017 - 02:34 AM.