An odd problem started the other day after I rooted my (Orange UK!) Dext, it wasn't immediate - I'm not sure what I did... anyway, the issue was that the default Android Browser wouldn't load any pages over 3G, neither would SkyFire, but Opera Mini would.
After some prodding and Googling I figured out how to fix it, here's how:
1. Navigate to Settings -> Wireless & networks -> Mobile networks -> Access point names
2. Select "orangeinternet"
3. Set the "Name" to "orangeinternet" (you must enter a name, and apparently there isn't one)
4. Select "Proxy" and clear the box (mine said "null")
5. Select "Port" and clear the box (mine again said "null")
6. Select "Server" and clear the box (again, "null")
7. Make sure the "User" is "user" (I didn't need to change this)
8. That's it, probably best to reboot the phone
That fixed it for me, hope someone finds it useful.