[bcr8u]

Beginning recently, I could no longer get to certain URLs using my ibook (OS 10.4). Most sites work fine, then some, like lowbudgethost.com (and the site I host there), about.com, doubleclick.net, and some others are unreachable. Trying to go to them returns a "server could not be found" error very quickly. I've also tried going to the direct ips of some of these sites, but that doesn't work either, so it's probably not a DNS problem. They are reachable through proxies. None of my other computers have this problem, and are set to the same exact DNS servers. I loaded a linux live distribution on my ibook and they sites work fine.
Any suggestions?

[wdonegan]

See if clearing your browser cache works.

[bcr8u]

I have tried clearing the cache, but the urls don't work in any browser. They're also unreachable by ftp and physically "dont exist" to the computer. I have also flushed the dns cache but that was no help either.