"virus out there that is called Microsoft Security Essential"

Too !?!? right, it patches itself into the execute stack so that it re-enables itself whenever you run ANY executable. I fixed it by booting off a CD and running AntiMalwareBytes, there's some good advice on the internet.

It calls itself "Microsoft xx Security Essentials yyyy" where XX is your current windows version and yyyy is the year after this one.

It presents a very convincing replica of the normal Windows security page, on the particular version I was eradicating there was one spelling mistake to give the game away.

When online I presume that anything that tells you instantly that your computer has an infection must be malicious - think how long it takes your onboard virus scanner to do the same job!