Internet Explorer will not display webpages beginning with www

I am using Windows XP Home 5.1 SP3 and Internet Explorer 8. For some
reason, starting today, I cannot access any webpages that start with "www"
names. I have confirmed I have network access, and I can display webpages
with non-www names, such as https://service.sap.com. But when I try any www
webpage, such as www.google.com, I get the "Internet Explorer cannot display
the webpage" message. I use TrendMirco and MalwareBytes for security, but do
not see anything in the settings that would cause www webpages to be blocked.
I also ran CCleaner recently to clean up registry settings, but I don't know
exactly what it cleaned up. Any ideas? Thx