Power on screen problem

[dexper]

Hello. Maybe someone has faced with the same problem before... When I turn off phone (standby mode) the screen starts powering on and off in different time intervals (for example/ 2 minutes after power off, it turns itself on... and few minutes after, it turns off again (or sometimes it takes less time)...) During the "оn" state,(when it turns on by itself) the touchscreen function is not working... I have to push power button 3 times untill it turns off, and then, when I turn it on again (with button) it works just fine. I am not sure is it software or hardware problem.

Model PH20B O2 XDA IIs WIN 2003
ROM 1.40.00 WWE (03/10/05)
Radio 1.12.00

Thanks!!