I had problem getting data connection (but only html it seems...) without WiFi on my Gemini the last day (and possibly longer; haven't been away from my home WiFi for a few days, and don't think I was using it the last times I was out either...). The kind of strange part was that I still had connection for my mail-program?
For some reason I couldn't get the SMS with settings working either (because the carrier doesn't "recognize" the Gemini??), but looking at the settings for the APN I think I found the problem: It had for some reason got a proxy-server configured/set. Clearing that got me my internet back...
Thought I should just post this for others who might have/get the same problem.