Problems using Whatsapp on HTC One V

I'm facing a problem using Whatsapp. Many times if I received 2-3 pics or a large conversation on Whatsapp, the phone's title bar (where it shows date, battery status & network status) disappears automatically. Also when I open Whatsapp it opens and disappears so in that case I have to select any pic/note & select option share on Whatsapp. Then Whatsapp opens after forwarding that pic/note. I have to use the option of clear conversation and then everything becomes normal. This is really a very irritating procedure. I don't know why this happens. Many friends of mine who use other company mobiles with the same configuration as my HTC One V don't have this type of problem. Please suggest what the problem is.