Laptop only loads about 4 websites?

Hey, posting this on behalf of a buddy I'm living with in the States..he has an issue where the only sites that will load on his laptop are pretty much Youtube, Facebook, Gmail( well, all google sites) wikipedia...and strangely boards.ie, which I discovered by chance... but essentially nothing else will load. I simply get a "This webpage is not available" for every other site. I can't go onto any malware sites to download things I'd normally use to scan a pc, he has AVG installed but that won't connect to the update server.
I suspect there's something funky with his laptop, as anyone else whose brought over a laptop and hooked it up to our router has been able to get on every site fine.

Any ideas why literally only four or five specific websites will work / load? It's wrecking my head! I can't even google for people with similiar situations as none of those sites will load!

Tried a system restore to no avail. Not sure what other options I have! Any Ideas? Was considering putting this in Virus & Malware, but I don't think that'd be it..