I'm not having the issue with Handcent at the moment. I also went in and updated my profile in the phone settings, and also sent a text to 9999 that said Allow All.
Try doing this:
Menu, Settings, About Phone, System Updates, Update Profile. You may want to update your PRL while you are there also.
Also, send a text to 9999 and put Allow All in the text just in case something is blocked (see link for info).
Support - Article
If all else fails, give Handcent a try. I did each of these things and am able to receive pictures now. Not sure which step fixed me. I hope it fixes your issue... good luck!