If it first started around the xmas changes it could be your computer has remembered those settings... Try a DNS flush, it will clear your old IP addresses and make sure it goes to the correct address, instead of attempting a usually quicker but sometimes wrong cache.

For macs not exactly sure but try here for info http://osxdaily.com/2008/03/21/how-to-flush-your-dns-cache-in-mac-os-x/ Darryl