How to capture the errors handling in Selenium RC using C# , Testframework: Nunit?

I'm using Selenium RC using C#, Test framework NUnit. My application throws the below error while running the link with code improper handled "A Runtime Error has occurred" in IE 7.0 and "Error on this webpage might cause it to work incorrectly" in IE 8.0.

But when we run through the test using Nunit in FF browser even though no results produced as output.It Passes the Nunit test. Could any one help how to capture the error handling in C#?

Any one faced the above issues? If so how it need to be resolved.