Every time we log on to Firefox on our home PC we get a message that it is infected with viruses and the only way around it is to purchase Vista Security. We can no longer access the internet. Is this a Firefox issue?

Sounds like Malware on that PC. Sorry, I don't know what "Deluxe Shield" is or does, but this is our standard recommendation to deal with Malware. Install, update, and run these programs in this order. They are listed in order of efficacy.<br />'''''(Not all programs detect the same Malware, so you may need to run them all to solve your problem.)''''' <br />These programs are all free for personal use, but some have limited functionality in the "free mode" - but those are features you really don't need to find and remove the problem that you have.<br /> ''Note: If your Malware infection is bad enough and you are mis-directed to URL's other than what is posted, you may have to use a different PC to download these programs and use a USB stick to transfer them to the afflicted PC.'' Malwarebytes' Anti-Malware - [http://www.malwarebytes.org/mbam.php] <br /> SuperAntispyware - [http://www.superantispyware.com/] <br /> AdAware - [http://www.lavasoftusa.com/software/adaware/] <br /> Spybot Search & Destroy - [http://www.safer-networking.org/en/index.html] <br /> Windows Defender: Home Page - [http://www.microsoft.com/windows/products/winfamily/defender/default.mspx]<br /> Also, if you have a search engine re-direct problem, see this:<br /> http://deletemalware.blogspot.com/2010/02/remove-google-redirect-virus.html If these don't find it or can't clear it, post in one of these forums for specialized malware removal help: <br /> [http://www.spywarewarrior.com/index.php] <br /> [http://forum.aumha.org/] <br /> [http://www.spywareinfoforum.com/] <br /> [http://bleepingcomputer.com]