Ext Js communication Failure

I am using Extjs in my application with J2ee framework. it happens that after working for sometime on my application I get a communication failure. There is no server side er开发者_如何学JAVAror.I have to delete cookies from my browser (i use IE most of the times) and then restart my browser and everything works fine. CAN I GET RID OF THIS PROBLEM?

Do you know the specific error. For a while, I was getting a 502 error. This turned out to be a concurrency problem - I was firing off a datastore load then immediately doing a refresh of my control. This error mostly showed up under IE6, less so on other IEs and never on FF.