Need core PHP/JS expert to solve refresh bug.

I basically have a chat system. The chat system has a right and a left side. The right side allows you to type messages to a person and the left side allows you to select the conversation you want to go to. Right now the entire chat system works flawlessly except for one thing. The one thing is that every x number of seconds the entire chat system seems to refresh instead of just the LEFT side. This is a problem because if you are a user trying to write a message the page would keep on refreshing and makes the chat unusable.

Please message me if you have experience solving these types of problems.

Thank you.