Help! Multiple browsers won't open a webpage.

I’m on a Macbook Pro running Lion and Windows XP through Parallels. Up until last week the Garmin Connect website had been working fine, but now it either doesn’t work at all or is incredibly slow. When it doesn’t work it generally gives a “server not responding” message. The thing is, it doesn’t work on any of my browsers, and all other websites do work. The Garmin Connect website works fine on my girl friend’s computer which connects to the internet through the same router as mine.

So, browsers it doesn’t work on, Chrome, Safari, Firefox, Internet Explorer, and Avant. All other websites work well on those browsers. The Garmin website works well on another computer connected through the same router.

What is it about my computer that is making it fail only on my computer? What should I be looking for? Presumably there is something in common between all of those browsers when running on the same hardware. I don’t have a firewall activated and I’ve tried emptying the cache and restarting the computer. Anything else I can try?