My Norton Internet Security 2012 recently turned itself off, some settings were changed, and then it turned itself on again. Is this something normal that it occasionally does, or has it been taken over by a virus that's changed some settings to make the NIS more vulnerable?
This concerns me a little more than it otherwise might because about a week before that, I'd started the computer in safe mode, did a full system scan which found a threat in a compressed file. Then, still in safe mode, I did another full system scan which found another compressed file threat (why didn't the first scan catch that?). The second threat was supposedly located in a folder normally excluded from Norton scans (which perhaps didn't apply while in safe mode?). Which made me wonder if the first threat didn't manage to copy itself there on purpose, and perhaps it didn't show up when I did a third full system scan because it had successfully found a hiding place from which it perpetrated the actions mentioned above. I've also run Norton Power Eraser, which found and "fixed" about 5 suspicious files.
I'm close to doing my taxes online, and would like to know whether or not I'm just being paranoid.
The compressed files found in the Safe Mode Scan were probably false positives. There is a bug in Norton 19.2 that causes this issue. It is fixed in the 19.5 patch. Norton Power Eraser, due to its aggressive nature, can also present some false positive detections - so unless you investigated its findings to confirm that they were malware, that scan, too, is not conclusive. If you are currently at the 19.5 version (check Support > About), then I would recommend a rescan in normal mode to see if your PC is clean.
Can you explain what you mean by Norton turning itself off and on. Are you meaning that the system tray icon disappeared, or something else? Did you notice anything else odd with the computer when this happened? What settings changed?
As far as the compressed file threats: I'd noticed my computer was acting weird while booting up. Turned the computer off and booted it in safe mode and ran the scans. Quarantining the threats hasn't caused any problems with normal operation that I've noticed so far.
As far as the suspicious files that Norton Power Eraser found, most of them were ".ini" files. They were listed as suspicious at first, I had NPE send them off for anaysis which came back as "Not a known threat." I checked where the files were located on my computer and found what appeared to be more than one copy of the same files, so I went ahead and told NPE to "fix" them. I've not noticed any problems with normal operation because of this, yet.
As far as the Norton turning itself off and on, I'd just booted up my computer and noticed that the Norton icon at the bottom had a red "x" over it. Turned the computer off and on, and it booted up normally. Checked the history and found some of the following events had occurred: