For reasons quite above my understanding, some (including mine) Linux systems are unable to access LinkedIn. Symptoms include hanging forever in the login page, i.e. you could access the authentication page, reading some and yours profile, but cannot do anymore.
This could fixed by issuing, as root:
ifconfig eth0 mtu 1360
(assuming that you reach the Internet via eth0).
It’s quite a strange setup, indeed. The only other time I had to do something like that was when I was trying to reach a Moodle server, that we had put on a LAN connected to the Internet via an ADSL consumer connection; the server was reachable from each customer of the same ISP but stuck for everyone else, everytime the poor guy requests a page whose size is more than or reaching the TCP/IP maximum payload (I guess this is for some kind of NAT magic/MPLS black magic/Peering sorcery that happens only for customers outside the AS).
I’m pretty sure that LinkedIn is not using a customer ADSL to connect itself to the Internet, and that they are seeing a constant loss of Linux customers due to this issue, which is very difficult to spot.