Selenium.SeleniumException : Failed to start new browser session: Error while launching browser

Hi,
When I tried to run the test using the Nunit gui (Selenium RC) , I am getting the following error: (I am using Selenium RC with .NET)
TestingBlogSeleniumRc.google1.TheGoogle1Test:
Selenium.SeleniumException : Failed to start new browser session: Error while launching browser
TearDown : System.NullReferenceException : Object reference not set to an instance of an object.

Can you please help?
Thanks for your feedback..

Thanks,
Kavitha

when you call the setup method.. provide the path of the browser
selenium.open("site url","*firefox C:\\Mozilla\\firefox.exe");

May be this helps

Regards
Ashish
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qtpselenium.com/samplevideos/selenium/seleniumvideos.php