Hello John-you may have a malware/virus or an application(s) that are constantly creating logs on your drive. Do you have good Antivirus software installed? If so, I would run a full system scan and go from there. Also, you may be able to extend your C partition into your D partition. I believe you have to format the D one though to clear its contents if you do this through the Windows disk management; so do make sure there isn't anything you need or want on the D partition. Also, you can download Piriform CCleaner (https://www.piriform.com/ccleaner/download/slim), which has a free version and doesn't have any other crap that will install when you install it. Run the cleaner and it will remove a bunch of garbage that may be on your C drive. Hope this helps you out some! Let me know if I can help any further! Ian