Once again sharing an experience just in case anybody faces the same problem. This happenes on Windows 7 x64 bit and Skype 5.
Basically, Facebook.com is blocked by OpenDNS in the network where this computer resides. On 3 computers, after shutting down at night and coming back in the morning, Chrome or Internet Explorer would open up at startup with multiple tabs, all pointing to the same Facebook URL, which was blocked. The URL was the following:
At first one thinks it's a virus, Spyware, or some Malware as we know these to cause this sort of behavior (pop-ups etc.) But the problem was Skype. After uninstalling and re-installing the problem was fixed. There are additional things that can be done, such as Selecting the Option Don't show Facebook in Skype, as we can see in this image: http://i52.tinypic.com/35aq815.png