Do these free anti-virus software sometimes install viruses on your computer and then clean them again to show how "effective" they are? I can't remember which software I was installing, my computer started hanging up so I went ahead and completed the download, only for it to find viruses which it cleaned. I was very suspicious of it. I am so sorry I can't remember which one it was.

I have no idea. Anyway I use AVG , and mcafee enterprise 8.5i edition. Mcafee is not a version version. You have to buy a license for mcafee. AVG is free and good for home users.

Luky one thing I really want to share with you is that, the Mcafee enterprise is not a free anti virus and also its not use for a single person (Home user). You need to buy a 1,2 years license after a time period.

i use avast anti virus that is fine for me as a home user.

This is my first time to hear an anti virus installing a virus and cleaning it up, Now I use Nod32 and it is effective for me.

Actually the one you had encountered is a scareware. There has been some legal fines regarding the companies which spread scareware in order to increase the sale of the softwares. I would recommend you to use super anti spyware software which would remove the malicious code running in your computer that your system is infected with virus, don't get fooled by it.

I know that the mcafee enterprise is paid and mostly it is used by a group or you can say a company.

I have heard of such scareware. My sister installed one of those programs and got infected. I use avast!Home antivirus program. It's free and very good. I haven't had an infection since then.