Currently malware are created often with the purpose of making money and sometimes to inflict physical damage (think Stuxnet). As we see a greater increase of computers in our home it is not surprising they have become a great way for cyber criminals to making money by exploiting them.
As a data security company we try to specialise and avoid requests for general IT support, antivirus installation or virus removals. Occasionally we get calls from distraught clients or sometimes even more draught client’s client desperate for assistance.
We saw two such instances involving ‘faux internet security suites’ in late 2011. A user was browsing a website or email and suddenly there genuine internet security suite disappeared and a fake one was installed. See below for an example:

Fake internet security suites will often disable genuine software, hide data and disable other functions which could remove it. They usually tell you that you have a virus but in fact they are a virus themselves! They are inconvenient to remove by can be removed by starting in safe mode, downloading a small piece of software to kill the process and then running an anti-spyware programme to remove it. This is not always successful as sometimes even more software is needed to unhide hidden files or software.
Every few minutes the ‘internet security suite’ will pop up and ask for payment. The advice we give is to not give your credit card details out! Even if you do the problem will not go away and you are left with paying for a service you actually need and still be left with the problem.
Note: Written in the start of 2012 but only just published - information maybe dated.