Are these links to sites that you know or suspect should be up and running? This could be an indication of malware that has installed itself on your system. I recommend you follow the first four steps of
this malware removal guide, to check your system for vulnerabilities. If you can't navigate to the sites on your computer, you will have to use another internet connected system and write the files to cd for installation onto your computer.
That should take care of it.
If this is simply an internet explorer issue, you might wish to have look
here.
If you are getting page not found errors, see
here or
here , or provide us a few more details, examples of links that aren't working, so forth.
I hope this information allows you to resolve this issue. If you need further assistance, please post back with a comment to this thread.
If I've managed to answer your question or solve a problem, please take just a moment to rate this post....thanks!