"The connection was reset" error

Question

I am getting "The connection was reset" error on my live server but its working okay on my local server. The thing is that I am having a drop down on a page, When the page is loaded drop down is filled with 2 values in it, I am able to select a value in the drop down and it is loading the content in all the other controls on the page based on the selected value of the drop down, Until here every thing seems okay. The problem erupts when I try to select a different value from the drop down, It is unable to connect to the server and showing "The connection was reset" error.
Please let me know what might have making this happen.

Thanks in advance.