Problem with Wi-fi connection

[Betatest]

Yesterday afternoon from unknown reasons rapidly reduced speed of the Internet. In the morning everything was fine - youtube videos went smoothly, online games to 50 ms. I have a notebook via Wi-Fi, and probably will be a problem on my PC, because roommate has the internet on his notebook completely at ease and even has better tests measuring results than me. It seems to me that from time to time it works fine, but then starts again. What may be a problem?

Thanks for the answers

 

[mammador]

It could be a fault in the NIC/Wi-fi card. Or there was something interfering with the signal.