How To Remove Viruses Before Your Operating System Starts

By using a bootable antivirus disc or USB drive

Most viruses are fairly easy to get rid of. Just open an antivirus scanner, wait for it to gather results, and then delete whatever it finds. Sometimes though, the virus just won’t go away and noregular antivirus solutionseems to help.

So, what are you to do with pesky, hard-to-delete viruses? Within the scope of antivirus software is an entire category of tools that do the scanningbeforethe operating system starts. Often called bootable antivirus programs, they scan files and remove viruses before they even have a chance to open.

Below are thebest ways to remove virusesbefore the operating system starts. If you’re not familiar with this process, we’ll go over all the steps, including how to download the scanner and what to do next to have it run at startup instead of your operating system.

Tip: If you get viruses often, learn how you should beprotecting your computer from hackers and malware.

How a Bootable Antivirus Works

There are two types of bootable antivirus software. One is a self-contained program that you have to install on a USB device or disc and then boot from it when your computer starts up. What happens is that the software on that device or disc is started instead of your operating system, and then you can run the scan and remove viruses from there.

The other kind is installed to your computer and functions like a normal antivirus solution, but within it is an option to also run boot-time scans. Just restart the computer and let the scan run its course. This is the easier method for most people, but it won’t work if the virus is so harmful that it’s not letting you start the operating system properly.

You’ll want to use one method over the other depending on your specific situation, so we’ll go over how to use both.

Use a Disc Or USB Device

The first type of bootable antivirus program isan ISO filethat you download to your computer and then put on a separate device so that you can boot from it.

There are lots of options for this type, includingTrend Micro Rescue Disk,Comodo Rescue Disk,Anvi Rescue Disk,Kaspersky Rescue Disk, andWindows Defender Offline. Some of these programs require a disc and others can be used with a flash drive.

We’ll use Adaware’s Rescue USB program as an example since it works with Windows 7 and newer Windows operating systems, can update its definitions before the scan, and supports custom scans.

Note: This software can also be booted from a disc, so if you’d rather do that, you can burn the program to a CD withImgBurnand then skip down to the BIOS step below.

Use Normal Antivirus With a Bootable Option

If the procedure above will take too long or is too complicated, or you don’t have a disc drive or free flash drive, you still have another option.

Some normal, installable antivirus programs have an option to run a scan and remove viruses when the computer reboots. They work in much the same way as the bootable AV tools mentioned above, but are far easier to use and do all the scanning and deleting automatically.

Some free antivirus with boot-time scanning capabilities includeAvast Free Antivirus,Adaware Antivirus, andAVG AntiVirus Free. All of these programs work a bit differently; Avast and AVG require you to specifically turn this feature on, while Adaware will run a boot-time virus scan automatically.

Let’s look at how to use Avast’s free scanner to remove viruses before the operating system starts:

This is what it looks like during an Avast boot-time virus scan. It could take a few hours to complete depending on how many files it has to check.

Take special note of the TXT file mentioned in theReport fileline. This should be the same for every computer; it’s where you can go after the OS starts to see what Avast Free Antivirus found and removed.

You can stop this scan at any time by pressing theEsckey. It will briefly tell you how many files were scanned and if any infections were found, and then your computer will reboot normally into the operating system.

Founder of Help Desk Geek and managing editor. He began blogging in 2007 and quit his job in 2010 to blog full-time. He has over 15 years of industry experience in IT and holds several technical certifications.Read Aseem’s Full Bio

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