I want to Avoid SQL Injection for my site in ASP.Net 4.0

Hi,
I am getting some errors after performing sql injection with firefox extension addon (SQL Inject Me). In My projecte i used Stored Procedure in order to save or retrieve data.
Some of the errors i got are below. Please let me know how to fix it. For all controls like  Hiddenfield, Textbox, Dropdownlist and  _Viewstate, __EVENTTARGET __EVENTARGUMENT, __EVENTVALIDATION.
But In My database no insertion was happening. How to fix this 500 Internal Server for ALL Controls.

Failures: 1258 Warnings: 0 Passes: 1080622 ctl00$MainContent$FirstNameTextBox Submitted Form State: ToolkitScriptManager1_HiddenField: ;;AjaxControlToolkit, Version=4.1.50401.0, Culture=neutral, PublicK ...