iTunes Store: "Error (-50)" when downloading purchased content or login to iTunes
Initially, I tried the guide in
http://support.apple.com/kb/TS1583 but it did not work because I do not have pending downloads.
I saw the guide below the article about msconfig.
I follow the guide in msconfig except I did not disable All services in:
and added these web sites under IE's Internet Options-> Security -> Trusted sites
and I got it working again after restart my laptop.