My primary dns server on my router seems to change by itself after a few days, it just happened a third time and I've had to change it back.
I'm not sure if this is a virus, or just something to do with my router's settings, although I did have my suspicions when the youtube page was redirecting to page with a link to download some setup to 'update flash'. The dns server it changes to has been different every time.
I have changed my router password just now ,also
I am currently using Windows 7, I've scanned with malwarebytes which came out clean, and also tdsskiller which detected nothing, avg is currently 60% through but nothing so far.