HTTP Error 500.21 - Internal Server Error

[fastestindian]

When I try to open a work flow i m getting following error
Web config setting
<!--STARTWORKFLOW-->
<add path="WorkFlowC ontroller.aspx" type="WorkFlowC ontrollerHandle r" verb="*"/>

Call from the page
Response.Redire ct("~/WorkflowControl ler.aspx")

Please click the link for error message.
Error

http://i43.tinypic.com/httslg.jpg

Please help me..i have absolutely no idea.

Thanks in advance.