When you use Microsoft Security Essentials, you can run either a quick scan of your computer or a full system scan. If malicious software has infected a specific area of your computer, you can customize a scan by selecting only the drives and folders that you want to check.
A quick scan checks the places, processes in the memory, and registry files on your computer's hard disk that malicious software is most likely to infect. A full scan checks all files on the hard disk and all currently running programs, but it could cause your computer to run slowly until the scan is completed. At any time, if you suspect that spyware has infected your computer, run a full scan. For information about scheduling scans to occur regularly, see Scheduling scans.
To scan the areas of your computer that malicious software is most likely to infect (Quick scan)
On the Security Essentials Home page, click the Quick scan option, and then click Scan now. The amount of time the scan takes depends on the number of files and folders being scanned.
To scan all areas of your computer (Full scan)
On the Security Essentials Home page, select the Full scan option, and then click Scan now. The scan may take a while, depending on the number of files and folders being scanned.
To scan specific areas of your computer only (Custom scan)
You can select specific locations on your computer to scan. However, if it detects viruses, spyware, or other potentially unwanted software, Security Essentials will then run an expanded scan to make sure it removes the detected software from other areas of your computer, if needed.
Running a custom scan
On the Security Essentials page, select the Custom scan option and then click Scan now.
In the Select the drives and folders you want to scan window, select the areas of your computer that you want to scan, and then click OK. The scan may take a while, depending on the number of files and folders being scanned.
To scan a specific file or folder (right-click scan)
If you suspect malicious software has infected a file or folder on your computer, or if you are concerned about something that you downloaded, you can select a specific file or folder on your computer for Security Essentials to scan.
Running a right-click scan
Right-click the file or folder on your computer, and then click Scan with Security Essentials….
Security Essentials will begin scanning the selected file or folder.
As soon as it completes the scan, Security Essentials displays the scan results.
Depending on the file size, this scan may take only a few seconds.