A concerned reader asks: Our son's laptop has started throwing up virus alerts for Antivirus 7.0. We've searched online for a solution, but can't differentiate between genuine advice and yet more scareware.

Antivirus 7.0 is a rogue program that pretends to find viruses on your PC and offers to remove them if you buy the full version. It can be removed quite easily.

Boot into Safe mode (press F8 when the boot screen appears and select Safe mode), then locate and remove the following files (Vista and Windows 7 users will need to use the search function to locate the AV folder within Users, since Documents and Settings is part of the XP file structure):

* %Documents and Settings%\All Users\Start Menu\AV

* %Documents and Settings%\All Users\Start Menu\AV\Antivirus7.lnk

* %Documents and Settings%\All Users\Start Menu\AV\Uninstall.lnk

* %Documents and Settings%\[UserName]\Desktop\Antivirus7.lnk

* %Program Files%\AV

* %Program Files%\AV\Antivirus7.exe

* %Program Files%\Common Files\Uninstall

* %Program Files%\Common Files\Uninstall\AV

* %Program Files%\Common Files\Uninstall\AV\Uninstall.ln

* %Program Files%\Antivirus7AV

* %Program Files%\Antivirus7AV\Antivirus7.exe

* %Program Files%\Antivirus7AV\unins000.dat

* %Program Files%\Antivirus7AV\unins000.exe

* %WINDOWS%\system32\UpdateCheck.dll

Next, locate and delete the following Registry entries by going to Start, Search (or Run) and entering regedit. Make sure you back up the Registry first.

* Hkey_Current_User\Software\EVAACD

* Hkey_Classes_Root\CLSID\{35A5B43B-CB8A-49CA-A9F4-D3B308D2E3CC}

* Hkey_Local_Machine\Software\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\{35A5B43B-CB8A-49CA-A9F4-D3B308D2E3CC}

* Hkey_Current_User\Software\Microsoft\Windows\CurrentVersion\Run "Antivirus7_

* Hkey_Local_Machine\Software\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent\post platform "WinNT-EVI 25.11.2009_

* Hkey_Current_User\Software\FNULL246

* Hkey_Local_Machine\Software\Microsoft\Windows\CurrentVersion\Uninstall\{6A23338A-C725-48D0-BA96-B12FDD22DD39}_is1

Reboot the PC and run a full antivirus scan using the free Microsoft Security Essentials.