I'm also having issues with the online basemaps. I've not used the feature for about 5 months or so. Today, I was going to see if the online Bing aerial map shows a newly built subdivision that our current in house map does not show. I can click on it and hit add, but nothing happens. Another ArcInfo user in my office was able to access it without issue on his machine. So I thought maybe I needed to reboot, as most issues on pc's are solved by rebooting. That didn't help. Any reason why one machine would be able to access the online basemaps, but another can't? Is there a setting I may have toggled? Could it be a software firewall issue? Both machines are identically configured and have been updated with ArcGIS SP5.