The Codec-C you speak of was probably installed as part of a movie you have tried to watch. Usually I see these installed when a user tries to watch a
movie format that Windows does not understand. Mostly, codecs are necessary however some unscrupulous types have found this to be a nice way to infect
Norton is ok. Don't panic! There isn't a single antivirus program in the world that finds every single piece of malware out there. Some are better
than others but overall - I'm finding the 2012 Security Suite to be quite ok, personally. I've thrown some tests at it (purposefully opening
infected files etc), and it's pretty active on most nasties out there.
Remember though - there is no antivirus better than common sense! If something is "free" on the internet, chances are there's a bundled surprise
waiting for you. This isn't always of course but some people don't host websites and provide "free" content out of the goodness of their hearts.
They are getting something out of it. Whether that be a fake type antivirus that demands your credit card to "activate" or keyloggers that record
everything you type on your keyboard, through to movie formats that ask you to install "codecs". There's something in it for them.
Free adult sites are usually where I find infections coming from. It's hilarious to hear some business employee who is infected up the wazoo with
porny popups deny they have ever been to any untoward websites!
I would strongly suggest running Malwarebytes. Download the free version from the link below & install. Ensure it is up to date by going to the update
tab and performing a definition update. I usually do this twice as sometimes you will find there will be more than one come through.
Re-boot your PC. Preferably in SAFE mode. To enter SAFE mode keep tapping the F8 key from the moment you restart your PC. A menu should come up with
Once Windows has booted (SAFE mode will load windows in a "basic" form minus many features and, most importantly - start-up items), you can run a
FULL system scan with Malwarebytes. Clean whatever it finds then restart your PC normally.
Malwarebytes free version won't provide real-time protection - it can only be used as a scanner so you can safely leave it on your PC if you like. It
won't conflict with Norton.
If you get stuck feel free to ask for any help. I have worked in malware removal / protection for an IT company for about 8 years