There have been more than a few DNS issues in the area over the past week or so, for those using DSL on Covad. This could be your issue.
I just corrected mine by going to Google DNS on one of my computers (I'll fix the others later). You can use OpenDNS or another service too, and get away from the Covad DNS issue. that seems to be occurring in the Sacramento area.
In my checks on the web, it appears to be an issue with several providers (sites), as well in the past week, so may not be Sacramento centric.