New owner seeking help

I have been reading a couple of threads and searching online, but still can't find anything useful. I recently purchased Nokia 5800 XpressMusic from Adorama through dealrocker discount deal. I must admit that it's really an awesome phone. I am impressed with the overall performance, but have a minor issue. I have many contacts in my phone. But in few contacts, when they send SMS to me, my phone doesn't show their name. It shows their number with country prefix in front. Can't figure out the problem. I am using the latest firmware. Can anyone help me to fix this problem.

Thanks..

first try factory reset....

any other problems then contact me on Msn

w.b.r
Gsm-Nikki
@hotmail.com