Hi, I have only joined UK Business forums this evening, so please excuse me for any inexperience in posting that may shine through.
I currently work full time for an Anti-Viurs company as a technical support engineer. I don't wish to promote them, so will not mention their name here. I am trying to start my own education, training and support company based on Internet safety and security centered around the knowledge I have gained at my current employer. Hence my reason for joining the UK Business forum.
When I saw stressman's original post I thought it would be worth adding my penny's worth to the discussion.
In a very broad sense, there are two types of virus infection: those that really are viruses and those that we class as fake programs.
Viruses of all sorts (trojans, rootkits, worms, etc) all do their best to hide their presence from the user. With out the aid of (any vendors) anti virus software, you wouldn't know your PC was infected. The virus might be part of a "botnet" where it is part of a network of thousands or perhaps even millions of PCs and used to send spam emails or attack corporate web sites such as the recent ones Sony suffered. Or it might be a data grabbing virus, intent on stealing personal and banking details.
Fake programs generally are very much "in your face". That is they make their presence highly visible, have an open window on the desktop that indicates your PC is badly infected or that your hard drive is about to fail or something similar.
These types of programs also make it look like the PC is completely broken. Desktop icons and start menu icons might have disappeared. Your web browser or other applications may not work. Their sole purpose is to get you to "purchase" the software, thereby giving the criminals your credit card details.
This type of program is actually very easy to get rid of, and the PC is usually perfectly ok afterwards. It is usually just one single executable that has been installed on your PC that starts when you start your PC. Delete it and the PC is very often perfectly OK straight away.
I apologise if this post is a bit long.
I would be interested to know what the symptoms of your attack were, stressman and if I could offer any further help or advice, I would be more than happy to do so.