W890i resetting

Hi there.

I'm having problems with my W890i, it resets its self sometimes, when i'm on a call or just using it in general. Is there a problem with the phone? Wat should i do? The screen goes blank then it vibrater once an the red light on the back turns on. If anybody could assist? Thanks
SonyEricssonW890i/R1FA Browser/NetFront/3.4 Profile/MIDP-2.1 Configuration/CLDC-1.1

It s very good!

It's perfect.