I'm having the same troubles with my SGH-i600 with ATT. Verified the settigns and get the same error message of "remote party disconnected."
The starnge thing I keep noticing is that after I put in the password for the GPRS settings and press "done", everything looks good. If I exit and go back into it, I see that there are twice as many "***"'s as there should be. It's as if it keeps reverting back to a previous passowrd? Or adds my new password onto the end of the original password. Or something. I can't seem to change the password.
Can this be causing it? Anyone have any experience or ideas here?