[HELP IN Mop] [urgent Technical ISSUE]

Whenever I play Battleground or Arena, after playing for like 5-30 minutes, I lag, like I can control my character but everyone is not moving, and even if when i Chat, it won't pop out. It's not my internet though because I was skyping with a friend and he told me that he can see me moving and able to control the character but in my screen, it lagged like no one's moving but the game is working perfectly after i restarted WOW MOP 5.4.8 but it keeps on happening to me :(

P.S. Not just in BG or ARENA but also when i'm afk for awhile it will happen.