This is a known issue on Tmo's network ( and possibly RIM's considering the amount of people that are experiencing this) A couple things to try that may help.
1) Go into menu, options, security options, general settings and turn the firewall on.
2) Go into options, advanced options, host routing table, menu, register now.
3) From the homescreen press shift + lglg and then when the event log comes up hit menu, clear log.
4) Pull the battery.
5) When the picture message comes in you will see the arrows in the top right corner. Do not open the picture message until the arrows have stopped.
This has helped fix the issue in the past but ultimately until the network issue is resolved i9t may come back. Hope it helps.