Most likely it's due to Hard Drive failure as most Vista computers are nearing 10 years old this year (from 2007); and Hard Drives are only designed to work for 3 years in Desktop PCs and only 2 years in Laptops!
If you've owned that computer since it was new and never had the Hard Drive replaced; it's 90%+ certain that it's failing or now completely failed!
After you try to upload your Disk Usage log to neemo; consider testing your Hard Drive and RAM sticks; replacing them if failure occurs. I have written a thorough step-by-step Troubleshooting Guide to assist you with the HW Testing here:
Windows 10 - Unclickable Task Bar
The Guide is quite long (6-8 pages), and so is a good idea to print out and have hardcopy in...