Run multiple antivirus applications on one PC

Fred langa By Fred Langa

Conventional wisdom says antivirus tools don’t work well together — so a PC should have just one tool installed at any time.

In most cases, that wisdom is still correct — but if you pick the right kind of software, there are ways to clean a PC with multiple AV tools.

Is it OK to piggyback AV applications?

Reader Steve Mutchler wants to use a custom suite of antivirus apps to thoroughly scrub a PC free of malware. But he’s not sure how to do it.
  • “I do a lot of virus cleaning for home users. For the most part, I slave a user’s hard drive to my computer and run my various AV tools on it.

    “I would like to have two or maybe three AV engines installed on my PC at the same time so I can run all three of them one at a time, because I think we all agree that no AV engine is 100%.

    “But AV tools don’t play nice together. For example, running Sophos and Webroot together, or Norton with most anything else, locks the computer up tight. Any thoughts on this subject?”

Full-time AV apps don’t work well together because each one integrates tightly with the Windows operation system. Having multiple AV tools simultaneously hooked into the OS — intercepting calls to disk drives, networking subsystems, and other system components — can cause major problems. In some cases, as Steve says, it’ll lock Windows up.

Disabling an AV tool’s top-level, user-controllable elements is not enough. Its low-level components remain in place — in some cases, still active and still able to interfere with other AV software you might install.

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All Windows Secrets articles posted on 2010-04-15:

Fred Langa

About Fred Langa

Fred Langa is senior editor. His LangaList Newsletter merged with Windows Secrets on Nov. 16, 2006. Prior to that, Fred was editor of Byte Magazine (1987 to 1991) and editorial director of CMP Media (1991 to 1996), overseeing Windows Magazine and others.