My Galaxy S2 has been failing to receive picture messages (MMS) since I flashed it with CyanogenMod a few months back. Not a big deal, but it was kind of annoying. No amount of fiddling with the APN settings seemed to help, and I was at a loss.
Along came ‘Tweakker’ a free android app that promised to correct my settings. And it did. First time. I rebooted my phone, and the picture message I had received earlier in the morning downloaded immediately!
Worth a shot if you flash custom roms, or your settings just flat out do not work. It’s free from Android Marketplace.