I purchased an unlocked Treo 650 GSM about a year ago - then about 4 months ago, the phone started turning off by itself.

I travel for work to countries in Africa, and use local SIM cards and the phone works fine. When I return and put the T Mobile Card in, it works for maybe a day, and then turns off. I can turn it back on, but it will turn off again in a matter of minutes or hours.

I tried getting a new TMobile SIM card, but this did not solve the problem.

Any ideas about what is going wrong or what I can do?

Thanks in advance for any help.