Aspire 4720
Chatting not working

I bought acer aspire 4720 in june from dubai.i am not able to voice chat in google as well as yahoo.i took this to near by customer care centre, they said they are not so sure as its vista, n they are not familiar too... i had purchased this from dubai, bcoz they had told me i cud get international warranty anywhere... here they told me i can get the warranty only in delhi or banalore..now tahts not possible..no hlp from anywhere