I haven't had this problem, but I initially had a problem with blocked phone calls going directly to voice mail for no reason. ATT tech support asked me to reset the iPhone. I did and it fixed it, for whatever reason. Many apps reccomend that users reset their phones if the app doesn't work well from the start. I suspect this applies mostly to non 32 GB 3GS models, since I have had very few issues and I have gone through about 200 apps. Good luck, and please post if you find a solution since I will be updating iTunes as soon as the 3.1.2 tethering config is available.