I have a sony ericsson. i have a sony ericsson w200i walkman phone, the problem i am having with

Question

i have a sony ericsson w200i walkman phone, the problem i am having with the phone is whenever i am playing music on the phone, it plays for a while and then says playback failed, also when i download application and games from wap to my phone, it says application error. I have a 1gb memory card on the phone.