file download servlet does not work on IE8

Hi all,
I've created a servlet which allows user to download a generated file (only two types of files: xml and xls). Servlet works perfectly on FF, Chrome, and Opera, but on IE8, when client calls window.open, a new window appears and diaspaears in a moment, just flush. I've done some research and find out that this is a common problem and can be solved by one of the following versions of doGet method. But none of those works with xml and xls files. I'm out of any ideas.
Here are methods found during research, all of them works on commonly used browsers but not on IE8
Do You have any idea?

Problem solved. It was not a matter of java code, but IE8 safety settings.
"Automatic prompting for file downloads" should be turned on.

Did you got any code solution for this

It's a client setting - there's nothing the web app can do about it.

I need to download mostly pdf files client settings is not an option for me.

chetan kapoor wrote:client settings is not an option for me.

Then you are out of luck. You cannot override the settings from code.