The Server Method "MyMethod" failed

Question

I am implementing Smart Search functionality on a text box in my mini project: When user type in a text box, the related contents are displayed in a div (using .innerhtml) on the same page.
 
To do so I have created a ASP.Net WebService. I am calling a WebService method "MyMethod" from javascript for each "keyup" in text box. It works fine.... but when user press so many keys then the service takes few time to respond, because n number of calls to the service method are there. Meanwhile, if user click an anchor to navigate to the other page, an error occurred: The Server Method "MyMethod" failed.
 
How to resolve it?
 

any reply would be highly appreciated....