For the last day or so Norton has been using every bit of CPU I had available, even while I've been actively using my computer, to the point I've had to disable tamper protection and limit it to one core. Earlier tonight, I start seeing "Analyzing file.xyz" messages, which is a telltale sign that Download Insight is trying to delete something I've downloaded... But I hadn't downloaded anything.
It turns out that for some reason Norton was checking files in C:\Program Files (x86) (and I'd assume a lot of other places too) and analyzing them. This is one of the files that was removed. (This and OpenRCT2, a community-made mod for Roller Coaster Tycoon 2). After the second file, I killed the Norton process, since something wasn't working the way it was supposed to.
I'm a bit confused as to why a "low-risk" file would be removed by Download Insight, as I thought it only went after meduim- and high-risk files, typically those that have been newly released. (Not to mention having no clue exactly what it was that triggered it, because of "Threat name: Unknown") I'm also concerned as to why Norton's Download Insight is scanning my files like this, since I thought it was only supposed to scan newly-downloaded/added files, and do it only once.