Ubuntu – Problem with internet. Certain website do not load at all. 12.04

My internet was working fine till tomorrow. Suddenly I am not able to open www.github.com, www.deviantart.com and additionally my router configuration page 192.168.2.1 . First, I thought that it would be a problem with my ISP (i have a DSL connection). I have a dual-boot system with win7, so checked the connection there. It all worked fine! Certainly it was not the ISP who was troubling, it had to do something with Ubuntu.

Problems and errors:

Github says:

This webpage is not available
Google Chrome could not load the webpage because github.com took too long to respond. The website may be down, or you may be experiencing issues with your Internet connection.
Here are some suggestions:
Reload this webpage later.
Check your Internet connection. Restart any router, modem, or other network devices you may be using.
Add Google Chrome as a permitted program in your firewall's or antivirus software's settings. If it is already a permitted program, try deleting it from the list of permitted programs and adding it again.
If you use a proxy server, check your proxy settings or contact your network administrator to make sure the proxy server is working. If you don't believe you should be using a proxy server, adjust your proxy settings: Go to the Chrome menu > Settings > Show advanced settings... > Change proxy settings... and make sure your configuration is set to "no proxy" or "direct."
Error 7 (net::ERR_TIMED_OUT): The operation timed out.

The same goes with the router configuration page, while deviantart takes forever to load.

What I tried:

I read some previous posts on this topic, and I tried the following:
1) I use google chrome. I switched to firefox on ubuntu but didn't work.
2) cleared the cache and cookies, but no.
3) Set the primary DNS server to google public dns, then to open dns, still nothing.
4) Tried to set the primary DNS to 192.168.2.1 , still no.
5) I reset my router, configured it from scratch in win7 and came back to ubuntu, to see that the problem still persisted.
6) pinged www.github.com and then google.com, here are the results:

PING www.github.com (204.232.175.90) 56(84) bytes of data.
64 bytes from github.com (204.232.175.90): icmp_req=1 ttl=53 time=390 ms
64 bytes from github.com (204.232.175.90): icmp_req=2 ttl=53 time=392 ms
64 bytes from github.com (204.232.175.90): icmp_req=3 ttl=53 time=384 ms
64 bytes from github.com (204.232.175.90): icmp_req=4 ttl=53 time=394 ms
64 bytes from github.com (204.232.175.90): icmp_req=5 ttl=53 time=396 ms
64 bytes from github.com (204.232.175.90): icmp_req=6 ttl=53 time=402 ms
64 bytes from github.com (204.232.175.90): icmp_req=7 ttl=53 time=397 ms
64 bytes from github.com (204.232.175.90): icmp_req=9 ttl=53 time=402 ms
64 bytes from github.com (204.232.175.90): icmp_req=10 ttl=53 time=397 ms
64 bytes from github.com (204.232.175.90): icmp_req=11 ttl=53 time=397 ms
64 bytes from github.com (204.232.175.90): icmp_req=12 ttl=53 time=398 ms
64 bytes from github.com (204.232.175.90): icmp_req=13 ttl=53 time=400 ms
64 bytes from github.com (204.232.175.90): icmp_req=14 ttl=53 time=399 ms
64 bytes from github.com (204.232.175.90): icmp_req=15 ttl=53 time=403 ms
64 bytes from github.com (204.232.175.90): icmp_req=16 ttl=53 time=404 ms
64 bytes from github.com (204.232.175.90): icmp_req=17 ttl=53 time=406 ms
64 bytes from github.com (204.232.175.90): icmp_req=18 ttl=53 time=403 ms
--- www.github.com ping statistics ---
18 packets transmitted, 17 received, 5% packet loss, time 31092ms
rtt min/avg/max/mdev = 384.510/398.374/406.145/5.407 ms


PING www.google.com (173.194.38.176) 56(84) bytes of data.
64 bytes from sin04s02-in-f16.1e100.net (173.194.38.176): icmp_req=1 ttl=53 time=132 ms
64 bytes from sin04s02-in-f16.1e100.net (173.194.38.176): icmp_req=2 ttl=53 time=130 ms
64 bytes from sin04s02-in-f16.1e100.net (173.194.38.176): icmp_req=3 ttl=53 time=128 ms
64 bytes from sin04s02-in-f16.1e100.net (173.194.38.176): icmp_req=4 ttl=53 time=126 ms
64 bytes from sin04s02-in-f16.1e100.net (173.194.38.176): icmp_req=5 ttl=53 time=129 ms
64 bytes from sin04s02-in-f16.1e100.net (173.194.38.176): icmp_req=6 ttl=53 time=128 ms
64 bytes from sin04s02-in-f16.1e100.net (173.194.38.176): icmp_req=7 ttl=53 time=133 ms
64 bytes from sin04s02-in-f16.1e100.net (173.194.38.176): icmp_req=8 ttl=53 time=123 ms
64 bytes from sin04s02-in-f16.1e100.net (173.194.38.176): icmp_req=9 ttl=53 time=131 ms
64 bytes from sin04s02-in-f16.1e100.net (173.194.38.176): icmp_req=10 ttl=53 time=119 ms
64 bytes from sin04s02-in-f16.1e100.net (173.194.38.176): icmp_req=11 ttl=53 time=127 ms
^C
--- www.google.com ping statistics ---
11 packets transmitted, 11 received, 0% packet loss, time 10009ms
rtt min/avg/max/mdev = 119.351/128.304/133.168/3.983 ms

I am positive that I have no proxy and IPv6 is disabled.

Please help me with the problem.