Problem with Kill marks

Hello! I have a problem with kill marks:
When i kill someone with a Head-shot using the RPK Infernal Dragon VIP, the game just closes and sending error report message appears, sometimes a white mark appears and the game closes and sending error report appears also ,But when i kill someone with a head-shot using any other weapon the kill mark appears and the game works fine.
I sent over 10 reports but nothing happens and the game still closes,Please fix this error