After wasting the better part of an hour diagnosing this problem, I have been told that our campus Websense device is blocking access to 74.125.95.100+, which is (in part) encrypted.google.com. (NB: I can't verify this, as I have no access to the Websense device.)

Can anyone corroborate this? I tried to reach someone at Google by phone, but they have excelled at making their telephone system and web site lack any obvious contact for such matters.