This is one case where having too much security can be a bad thing. Having more than one antivirus client installed on your laptop or desk top computer at the same time can cause havoc to your system. To make matters worse, many antivirus clients do not uninstall correctly, and leave behind pieces that will either cause your new antivirus software to not install, or cause problems with your computer.
If you are installing antivirus on your computer, or switching to a new antivirus client, you will first want to make sure that no antivirus is still installed on the computer. You will want to check your programs and features list and Windows 7 and Vista, or the add and remove programs list with Windows XP, to correctly remove any antivirus already installed on the computer. If you did have antivirus installed previously on the computer, take note of what brand you were using. Some antivirus clients such as Norton and McAfee, are notorious for leaving behind pieces of their install after the software is removed. If you did have a Norton or McAfee product installed on your computer, after you uninstall the product and restart your computer, you will need to download a removal tool to make sure the uninstall is fully completed. You may want to search the Internet for the brand of antivirus you were using to make sure they do not have a removal tool to use after uninstalling the software, but Norton and McAfee are the most common to have this issue.
Having more than one antivirus client on the computer at once will only cause problems in most instances. Imagine that one antivirus flags a file and moves it into its quarantine folder. Now the other antivirus client sees that folder as having an infection inside and tries to quarantine it to its folder. You can see the problems that can arise with two antivirus clients fighting with each other. It is also an issue because antivirus clients tend to be tied into many Windows system files and having two pieces of software tied into the same files can cause problems. Now not all security software is antivirus software. Examples of antivirus software are Trend Micro, Norton, McAfee, Kaspersky, Eset, AVG, Avast, Avira, Microsoft security essentials and many others. Spyware and malware programs are different. Most of these can be installed alongside your antivirus client. Examples of these are Adaware, Malwarebytes, Superantispyware, spy bot and many others. Some spyware and malware programs such as webroot spy sweeper and spyware doctor have antivirus software combined with and you want to disable the antivirus software or choose not to use these products with already installed antivirus software.
If you are truly worried about the security on your computer, the first step is using a paid antivirus versus a free one. You can see our blog post on paid antivirus versus free antivirus here. Paid antivirus will give you much more protection than free antivirus. The rogue security infections going around the last year or so tend to go right through most free antivirus applications and even some of the paid ones. The next step is to make sure that you’re updating Windows, Adobe, and Java. Most of the updates for these products are security updates that help patch flaws that viruses use to get into your computer in the first place. I would also recommend web of trust for a browser add-on, it will help flag unsafe websites ahead of time for you. Once you have a good paid antivirus client installed you’ll want to make sure it’s updated and that she run a full scan monthly at least. You can even see if your antivirus client is doing its job, by using free online scans from many vendors, like Trend Micro housecall, or Eset online scanner, or even Hitman Pro. You may need to disable your antivirus client before running these online scans just remember to re-start your antivirus after the scan has finished. I would also run a spyware clients such as Malwarebytes or Superantispyware alongside the antivirus client for extra security. You will need to scan with both of these programs to check for security issues as they only offer real-time protection in their paid versions. Using Malwarebytes or Superantispyware in real-time versions may conflict with your current antivirus, so I suggest you use the free version and just make sure to update and scan your computer frequently.
You would be surprised how many computers we get in for service that are not running correctly, and in some instances can’t even boot up, all from having too many antivirus clients installed. We even see computers that are infected with viruses because the multiple antivirus clients are fighting with each other and not able to do their job.