CSV issue

Data shown in grid. User has the capability to select a row or all rows from the grid and click submit

button to get data from the database. This submit button can bring back the result set in html or xml or csv format based on users selection. Now the issue is related to CSV. If user select a row or more rows and select to get the results as CSV, result comes back as csv. Now if user close the csv file and select differnet rows and select to get the result as csv ,result comes back as csv . This time user does not close the CSV file of previous selection ,but select differnet rows and try to get results in csv, it brings back the previous result set in the new window, and empty out the previous window.Seems like variables does not get reset in the new selection when previous selected record of CSV file is opened. But this behavior does not happen for HTML and XML.

Can anybody help me?