Laptop

Firstly don't worry, virus's are not going to descend on your computer straight away. What sort of window is being displayed, is it coming from the MS security centre?

 

What version of windows is this on? Trying to figure out what is actually saying that the Anti Virus is off, whether it is a message from windows or somewhere else.

 

Is this a popup window of some type saying the antivirus is off? If so, what does the title bar say? Are there any other parts to the message?

 

Which Norton products do you have installed? Norton has a few different products, and occasionally they won't properly talk to the windows functions that report if antivirus or firewalls are enabled.

 

First off, Norton is NOT protecting your PC. Look around online. It's most likely letting stuff in. Get Microsoft Security Essentials, which is built with Windows 7 in mind. Run a full scan upon installation of Microsoft Security Essentials, and now have peace of mind with your PC.
Microsoft Security Essentials - Microsoft Windows

 

MSE is pretty good but it doesn't catch everything (Like everything). The current version of Norton isn't actually that bad but it is essentially a rootkit that installs and hopes to function like an antivirus. Good thing is that it is hard to disable, bad thing is it often detected by a rootkit (And likewise I remove it when cleaning machines) and it is a rootkit. I just don't like stuff hiding in that part of my OS.

I've used Avast for a while and it works well though, free w/registration (Free, no spam). Nod32 is good too if you want to pay for it. If you have a rootkit then there are ways to remove them, relatively simple ones too although there is always a data loss risk (Rkill + ComboFix stops most stuff pretty quickly).

I'm actually amazed at then new MBR stuff that hinds in those catches, it is spread often by a rookit that sets in and most of the time gets overlooked; that was the whole reason for the use of UEFI booting in W8 (Although GRUB and other boot loaders don't have an issue, just windows ones).

Anyways if your really worried you can grab a CD and burn a live disk of something like the Kaperspy cleaner onto it. That would be able to get a good check of the system without you having to worry about malware interfering. Malwarebytes is good scanner that picks up things too.

Beyond that you could grab a hijackthis log and post it here, shoot me a PM or something and I'll give it a look over. That should be able to tell me if there are any bad things running at the time, although some things aren't easily visible.

A lot of time MS is just wrong though, I've had it tell me things are OOD and stuff when they are really the ones out of date.

 

Yeah, Avast is pretty good, as well as Kaspersky and ESET. You should also do a full scan with Malwarebytes every so often, and have a system image backup.