Default Unknown calls mute ringer volume

Hi I have some strange problem after rooting my htc desire. My ringer volume becomes zero as soon as I get calls from Unknown number(ringer becomes zero at start of call automatically). Any solution? I tried going back to stock rom but no luck. Is there any way I can complete wipe stock rom and get new one. I am running 2.2 software version 2.12.110.4 and baseband32.49.00.32U_5.11.05.27. I tried to flash with
RUU_Bravo_Froyo_HTC_WWE_2.29.405.5_Radio_32.49.00. 32U_5.11.05.27_release_159811_signed
but it didnt work. Any help please, any program etc its annoying.
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HTC Sensation Z710e (1GB), S-Off, Super CID, Sense 3.6, Rooted
RUU_PYRAMID_ICS_HTC_Europe_3.33.401.53_Radio_11.76 A.3504.00U_11.24A.3504.31_M_release_280871_signed
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HTC Desire, S-Off, hBoot 1.8, MIUI XJ 2.3.7