hmmm.
Did you try using the IP address method above? You can just click on those links and that's a simple test.
One additional relatively easy thing to try -- reboot everything:
1) power off your computer, the DSL modem and anything connected to it (wireless routers, hubs, etc.)
2) Unplug the DSL modem.
3) disconnect EVERY device plugged into your house phone lines (including the DSL modem and all your phones). Make sure you got them all. One time my daughter had plugged a "barbie" phone into one of the wall jacks without my knowing it.
4) Wait five minutes then plug in just the line to the DSL modem and computer, power it up, and try it again.
If you're using a wireless router, take that out of the loop to eliminate wireless questions.
On rare occasions power surges or line noise will interfere with my Bellsouth DSL routing until I sort of "re-boot" the phone lines.
If that does nothing, I'm inclined to agree with Kurt. Other things to check are pop-up, spyware, or adware blockers, anti-virus software, or firewall software that could be blocking specific sites.