I recently ran three on-demand scans of a usb external hard drive. On the first scan I did not select "clean" - there were eight files with detections, and the run time was 4 hours 15 minutes. The second scan I did select "clean" - there were eight file detections, one could not be cleaned or deleted, and the run time was 4 hours 7 minutes. I navigated to the folder containing the detected file and the agent popped up with the detection and deleted the file before I had a chance to even try to delete it manually. I ran the scan a third time (set to "clean) and it ran clean with zero file detections, with a run time of 6 minutes. My question is "Why did it only take 6 minutes for the third scan?" Any insights would be greatly appreciated.
I can only assume that it skipped files that had been previously scanned or, and more likely, the problem file was perhaps compressed and apart from being suspect the software had problems unpacking it, but once it was quarantined then the rest of the drive was a simple fast scan. There could also have been a delay in the software communication with the database to check if there was a record of it. Communications with servers in the USA/Canada are patchy at the moment due to tropical storm Sandy and that may be contributing to delays.