Problem with 7100i's service book

[benjin89]

Hi, I have the boost $50 plan. Just bought a 7100i off ebay. phone call and walkie works fine. I followed the instruction to put the service book on it. Everything works fine for the first day. I can surf and text. But the next day, I reboot the phone. After i turn it back on, most of the service book entry are gone except 5 of them. I can still surf the net, but the mms service is not working. I did the process again. Everything started working. But once I reboot the phone, the service will be gone again. Is this the problem with the phone or is it something wrong with the service book setting? I updated everything to the newest version and it doesn't have it policy on it. Please help. I really need it working. Thank you in advance.