suspicious page not found errors

I have Windows XP, IE 6.0, and a 56K modem. I currently use Juno as my ISP via the telephone line. I have been getting unpredictable "page not found" errors when browsing the Internet, roughly 20% of the time. The problem manifests itself in one of two ways:

(1) (most common) -- I type a URL that I know works, but it says page not found. I click refresh or retype it and suddenly it works. Sometimes when I pull up an email in my yahoo account and then click the link to return to my inbox, I get the page not found error too. This is but example of many URL's this happens with, the problem does not seem to discriminate.

(2) (less common but happens often enough and very weird) -- When I type a URL in the address line, e.g. "www.yahoo.com", on the bottom left of the Internet Explorer screen it says "searching for www.www.yahoo.com.com." It doubles the suffix and prefix and then tries several other suffixes, e.g., www.www.yahoo.com.edu, resulting in a page not found error.



Here is what I have tried so far:

(1) upgrading from Windows 98 1st edition to XP
(2) reinstalling IE 6.0
(3) reinstalling Juno


I hope it is not a virus, although I had one at one time that has since been removed to my knowledge. Does this sound like a DNS error recurrence on Juno's end? It's driving me nuts. Thanks

Marc