after surfing the internet on this issue for over 24 hours now ! the only answer i got was that no one has a clue about the solution or what is causing the problem !
in this case i am tempted to think that it is a hardware problem !
what is weird is that the phone is working fine now (crossing fingers)
but as soon as i will use my bluetooth or headset i am sure the problem will come back !
until now i have stoped using my speakers and bluetooth ! i think with only 4 to 5 months left for the 3gs to come out in our region ! it wont be wise to buy a new iphone 3g right now !
i will continue updating this post too !