I have had this problem before: I am using nciku.com, the website manager is not the best, and it has downtime. My isp somehow 'sees' that the webpage is unavailable, and redirects me to
www.jscity.net/dns/?host=www.nciku.com, which is a kind of news/info site.
The next day, I try and I think, nciku.com is still not there, but when I start the girlfriend's Win laptop, it is available.
So I go to Firefox window >Help>Troubleshooting Information
There is a button: Reset Firefox.
After that, I can reach nciku.com again.
Is this a Linux problem, a Firefox problem, or a combination of both?