Nokia 5220 Xpressmusic — my phone restart often

i am akshay niphadkar from pune, i purchased nokia5220 xpressmusicc phone with 1 gb cardat 28-may-09 for rs 7200
within a week i start facing problem like, mobile restart atomatically, i couldnt personlize ringing tone, when i try to put song one after one it restar,

my mobile has only 120 song no additional software, then why it is restarting,
i feeling cheated right now, its just waste of money
please help me i[censored] can