I never heard of that happening before so I'm not sure how it occurred.
There are three types of scans offered by Windows 8/10 Defender and most other anti-virus/anti-malware programs:
- Quick Scan only checks the areas of your computer most likely to contain malware...the most prevalent and common places where malware typically hides. The length of time for performing a Quick scan will vary but it generally takes about 15-30 minutes so they can be performed daily.
- Full Scan is much more comprehensive since it scans the entire hard drive (all folders/files) which can number in the thousands. The length of time for performing a Full scan will also vary but because it is so comprehensive, this type of scan can take several hours. Most Full Scans can be scheduled to run late at night when not using the computer so you can perform a weekly scan without having to monitor it.
- Custom Scan allows the user to select any files and folders on the hard drive to be scanned.
In most cases when performing routine security checks, only a Quick Scan is needed
since it checks the areas of your computer most likely to contain malware...the most prevalent and common places where malware typically hides. A Full scan is generally recommended only for heavily infected systems.