This is general information about scanning which may be helpful toward understanding things you may encounter from time to time which can be used for future reference.
to complete an anti-virus or anti-malware scan depends
on a variety of factors
-- Using two security scanning engines at the same time can cause each to interfere with the other, cause systems hangs, false detections, unreliable results and other unpredictable behavior.
- The program itself and how its scanning engine is designed to scan: using a signature database vs heuristic scanning or a combination of both.
- Options to scan for spyware, adware, riskware and potentially unwanted programs (PUPS).
- Options to scan memory, boot sectors, registry and alternate data streams (ADS).
- Type of scan performed: Deep, Quick or Custom scanning.
- What action has to be performed when malware is detected.
- A computer's hard drive size.
- Disk used capacity (number of files to include temporary files) that have to be scanned.
- Types of files (.exe, .dll, .sys, .cab, archived, compressed, packed, email, etc) that are scanned.
- Whether external drives are included in the scan.
- Competition for and utilization of system resources by the scanner.
- Other running processes and programs in the background.
- Interference from malware.
- Interference from the user.
-- If the screensaver, hibernation or Sleep Mode are not turned off before scanning, those features can sometimes have odd effects when attempting to resume normal mode.
Further, it is not unusual for an anti-virus or anti-malware scanner to be suspicious of compressed
, and packed
files because they have difficulty reading what is inside them. These kind of files often trigger alerts by security software using heuristic detection
because they are resistant to scanning (difficult to read). This resistance may also result in some scanners to stall (hang) on these particular types of files or just ignore (skip) them. Certain files in the System Volume Information Folder
like the Tracking.log (created by the Distributed Link Tracking Service to store maintenance information) have also been reported as a source causing some scanners to hang.