Back-up format and re-install. If it still refuses to let you access the network then it's probably a hardware issue, if it works, then you probably had a virus or something. I'd also recommend not using Norton and using MSE which is free combined with Malware bytes which is also free, provided you're not ignorant enough to download and run "cum_guzzling_sluts.mp4.exe" then you shouldn't ever have a problem with viruses.
Also as added protection, install an adblock, pretty much most viruses you'll encounter will be through shitty adverts, block those and you will be much safer.