8210 finding networkthen loses network,thenfinds again

hi ,
i,ve an nok8210 that has this strange prob:phone finds the network,then loses network,after around 2-5mins,then 30secs later finds network again,sometimes then it will stay with networkfor 2-3 hrs,but always loses network,for around30secs,all this without even moving the phone(phone placed in same location all the time).when it gets signal it is full.i,ve reflowed the phone,reset software,do you think this is hardware prob,or do i need to flash new 8210 software,anything you have to say on this prob will be very much apreciated,
also this happens on both 900 and 1800
thank-you

Try replacing the PA and run a test with eeprom tools by b-phreaks will normally tell you some of the faults with phone!

Try to open your tones and play it if the tone that before this come fast then come slow i means the slow play with slow music like the tempo goes 40bpm but it show 225bpm just change the 32.768khz crystal clock