I run a program called Ad-Aware every couple of weeks, so I don't think that is the problem.
I may be struggling to explain my problem properly as I'm not totally au-fait with computer jargon.
I can access websites, its just that it can take several clicks on the link to get there. Its as if its timing out after a couple of seconds. It tries to get there, but defaults after a couple of seconds to the 'this page is not available' page. A second, or third, click often does the trick.
Sometimes, however, it just won't access the page. Ten minutes later I might be successful.