Dissapearing web pages

Some time ago my computer was upgraded from windows 98 to Windows 2000. I promptly loaded Service Pack 2 and 3. My Internet Explorer is Version 6.0.2600.0000, 128 bit, with Update versions Q321232 and Q323759 loaded. I have noticed that many web pages are no longer accessable on my computer. As soon as a particular web page starts to load, I am kicked back to the Desktop instantly with no explanation. This even applies to some web pages I have in my favorates which I used to use regularly. I cannot see any pattern to the web pages I am being tossed out of. I am assuminmg the problem is in Internet Explorer, but I don’t have a clue.