Sounds like a simple case of a bad DNS update that should clear up in a few days max. You can try to speed that along, but there's no guarantees it will work.
Open up a DOS prompt and type in (without quotes) "ipconfig /flushdns" and hit enter. It should be almost instantaneous.
The problem could be that your ISP's DNS server has a stale entry, and if that's the case, you can only wait until the next refresh which should be every couple of days tops. I am assuming that when you say your friend is on "the same DSL" you mean came to your house with a laptop, connected to your router, and tried it. If you just mean he has service through the same company, then they have a bad DNS entry, and you'll just have to wait it out.
That being said... IE is a notoriously insecure web browser, and you would be well advised to find an alternative. You can take your pick between Firefox, Safari, Opera, and Chrome. There are a few others out there, but those are the major players. All four are free, so give them all a try and keep the one, or ones, you like best. Reserve IE for those rare pages that absolutely will not load with anything else, and you absolutely need to be able to use.
When I try to access a website I have visited for years, I get an error message from Internet Explorer that it cannot access this site. I have contacted the webmaster and she says it is all good on her end. I have contacted my DSL webmaster and he says the signal is being received and sent out fine. He suggests it is my computer. My friend tried this website (he is on the same DSL) on three different browsers and received an error. My other computer also receives this error. What is going on and what can I do about it. I am wondering how many other websites I have tried to visit and wrote off as bad addresses as IE gives me and error. Thankyou. This is the website and I can access this but not any of the links. Also they send me a newsletter and I cannot access any of the links. ?? http://www.hp.com/united-states/hho/classes/?jumpid=hpr_R1002_USEN