Unable To Access Internet

Hello, my name is Kim

I am trying to access the Internet with my Dell Alienware X51 R2, but I can't, and I don't know what else to do.

I'm never connected to the Internet with the Dell (my main internet computer is my Mac), and the only time I connect, is when I need to download/activate digital softwares, and update my Dell. Usually, I connect just fine (I connected my Dell to the internet about 2 weeks ago), but today, when I wanted to download/activate a music software, for some reason, I could no longer connect. I verified, and I have no virus, nothing to prevent such connection. I also did not change any computer settings or deleted files in the 2 week since I last connected my Dell to the Internet.

Finally, I have followed every fixes in this troubleshooting article:

www.online-tech-tips.com/.../

But still nothing happened. I can't connect to the Internet. I've tried with both Internet Explorer and Google Chrome.

I double-checked, and I can use the same internet (I use an Internet box receiver, not a WIFI) on my Mac computer, and it works, so it doesn't seem to be the problem of the box receiver.

I restore my computer, uninstalled and reinstalled the network card, etc, followed every tips in the article above, but at the end, still can't connect to the Internet. 

In the troubleshooting result it gave me, it told me that the computer was configured correctly to receive the signal, but the problem might be my DNS server; however, as I've said above, my internet box works perfectly fine with my Mac. And again, my Dell is never connected full-time to the Internet, though in the past I could, like 2 weeks ago.

Is there anything left to do? What's the problem? 

Thank you,

Kim