I cannot see any text in the body of the mail messages i receive in my yahoo account?

I cannot see any text in the body of the mail messages i receive in my yahoo account but i can see the mail headers displayed properly.Only the body is blank.Is this some form of virus activity.The problem started on 12March2007.Kindly advise .I have tried deleting cookies and clearing history.....I have also tried ---rt. click and auto selecting the encoding ....nothing seems to work. Am I doomed ?