Problem in adding the in the text box.

Hi

I am having a text box and drop down. In drop down selected index change event, i used to bind another drop down.

When i add the "<Category>" in the text box and try to change the drop down it leaves me an script error saying.

"Microsoft JScript runtime error: Sys.WebForms.PageRequestManagerServerErrorException: An unknown error occurred while processing the request on the server. The status code returned from the server was: 500"

when i add a text without using "<" and ">", there is no error occur.

Can any one help in this issue.