Please help: I cannot access my facebook account on my new HP laptop.

Okay so I have kind of a huge problem. Well not really I'm just being a bit dramatic. lol. I have recently gotten a new laptop (HP Pavillion dv7-6157cl / Windows 7 Home Premium) and since I set it up I have had a problem signing into facebook. The only time I was able to do so is the day I got it, when my sister installed some add-on but it stopped working less than an hour later. I am able to access the web page but am unable to sign in. At first, I would put in my information to log in and I would see a message saying I had to enable cookies.. So I did that and I still get that lovely message sometimes and I go to my internet options and the cookies are enabled. -_- But what I usually get now is "You must log on to see this page" after I attempt to log in. I know my log in information is correct because I am able to log in on my Android, so that is not the problem. Also, I have restored the internet settings to how it originally was and nothing. Another problem that I had, which I mention just in case there is some correlation to the problem at hand, is that I was having problems logging into my gmail and youtube account. The problem was that I was checking the box for "Stay signed in." So when I didn't check that box I was able to sign into both. Oh and I am trying to refrain from using any other web browsers because some have told me that it is easier to get viruses and that they cause unnecessary problems that may easily be avoided. Okay so I just gave the most thorough explanation of my dilemma that I possibly could, I truly hope someone is able to help me fix this problem before I am forced to take my birthday gift back. Thanks!
-♥.Bell

You guys are freaking awesome! Thanks! I had a feeling that would work but was afraid of messing up my computer since a lot of people believe that viruses come from these kinds of programs. I had to ask someone who actually knew what he/she was doing. lol. You guys saved my life! Thanks again!