Biult in Webcam problem

Question

Hi, I'm using an HP Pavillion notebook. I don't have any problem using my yahoo messenger version 8.1 before
until last night when I used my built in webcam on Yahoo messenger. It
crashes when i invite someone to view my webcam. I also have problems
with the call function because I can't call nor receive a call from
someone. I tried uninstalling the yahoo messenger and reinstalling it
but nothing happened. Please help and thanks for taking time to answer
my query.