I'm in the process of upgrading (memory and adding internal drive) a 5 yo Dell XPS 8700 desktop because of general slowness but am first trying my best to clean up computer and troubleshoot a common 100% disk use issue. I (re)installed the free version of MB and found a few threats on my 1 TB hard drive, quarantined those, and then decided to scan a 8 TB external drive that is usually connected and is nearly full (might be the problem?) mostly with disorganized backups and recovered files and a lifetime of my own photos (i.e., not risky stuff pulled off the internet).