When attempting to install some new software on my Windows XP computer a message appears during the installation wizard that says “The following error occurred on file: C:\WINDOWS\System32\ioctlvdd.dll. Access is denied”. Around the time this error began to occur I remember that a Trojan virus or alike was detected, quarantined, and deleted. Do you have any advice on how this problem can be solved?

When searching the web for the “ioctlvdd.dll” file, all the results mention virus and malware infection instances. Given that I have not heard of this file before I am guessing that it is related to the particular virus on your computer. I am unsure why the installer is attempting to access or modify this file, since it seems like the file is purely related to the previous infection on your computer as opposed to being any kind of system file included in Windows (otherwise there would have been a lot more search results for that particular file). This leaves me concerned that there still may be portions of the infection remaining on the computer.

As you may have read in previous columns, I consider that once a computer has been infected with a virus or malware that computer can never be trusted again until the hard drive has been wiped and the system reinstalled from scratch. This is due to the risk of something remaining behind – even though virus scanners try their hardest to remove any detected threats, it would be impossible to guarantee that the infection is completely removed simply because there are too many variants and variables at play with such infections. In this case because the only references I could find to that file relate to a virus infection, and there doesn’t seem to be any other reason that file would be on your computer or any reason it would affect the installation process of another program, signs point to parts of the infection remaining behind. Unfortunately, my research into this clue has not yielded the name of the infection on your computer but only generic information about this file.

Given that we simply don’t know why this error is occurring, but we have good evidence indicating that the file in the error message is related to a virus or malware infection, the safest course of action is to backup all data on the computer that you wish to keep, then format the hard drive and complete a clean reinstallation of Windows. I realise that this is not a particularly convenient task to complete, but it always pays to be safer than sorry particularly when dealing with IT security and potential infections. I am also unaware of which antivirus package you are running at the moment, but if you are in the market for a new antivirus package then Microsoft Security Essentials (windows.microsoft.com/mse) is a good, free antivirus package provided by Microsoft. Alternatively, if you would like a more fully-featured commercial antivirus product, then ESET NOD32 Antivirus (eset.com.au) is a good product which has a relatively light footprint and is not too resource intensive on your computer. Make sure that you fully update Windows, install antivirus and update the antivirus before transferring your files back onto the new installation of Windows (just in case there are any remaining infected files on your backup medium, as hopefully the antivirus on-demand scanner should pick those up before they are copied to your computer).

Also, a word of warning. If you search for the “ioctlvdd.dll” file in Google (or other search engines) you will likely be presented with a whole host of websites which have claimed to have “scanned” your computer for problems and detected various issues, particularly with the “ioctlvdd.dll” file (amongst other things). These sites are bogus and do not actually scan your computer, so please ignore any such messages or fake scans. They are simply picking-up on the keyword which you have used in the search engine (in this case, ioctlvdd.dll) and then putting that into placeholders on their web pages to give the impression that they are there to fix that particular problem and try to charge you for the privilege! As a rule of thumb, never ever purchase something from a website which claims to provide a solution to your very specific computer problem. As a more general rule, never purchase anything over the internet unless it is from a known reputable source.