Windows Mobile 5 keeps on restarting

I possess an HTC from O2 mobile communication. The warranty is over since this mobile is an old one with the operating system to be of windows mobile 5. The physical description of the phone is that it is a rather big one with a tap-screen. I am really attached to this phone. Lately it has been through some troubles. One year back, I noticed it to restart whenever I use too much of internet from Wi-Fi source.
I usually format it to factory settings on approximately semester basis for the phone not to be too overloaded. I prefer having it for calls and music listening. Internet browsing has not been recently my activity. The Wi-Fi hardware on the phone works on and off. I guess the phone has become too old. Recently when I reset the HTC to factory settings, the phone would not load, instead it would show windows loading screen just like a computer screen when windows is loading and before coming to my mobile desktop, it would restart. It keeps on doing that for several restarts before coming to a white screen. Is my HTC mobile phone dead?
