Export to Excel..page throwig error "The connection to the server was reset while the page was loading."

 My data is being exported nicely but i dont get open/save box neither does my excel sheet gets open automaticaly..instead i get error The connection to the server was reset while the page was loading....
i have added:
<httpRuntime executionTimeout="600" maxRequestLength="51200"/> 
to my config file
but i still getttin same error

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