http 500 Internal server error after putting the login credentials

Hi,

I have created a web appplication & site collection in sharepoint 2010 with the following details:

Claims authentication

given Host header name

made entry in the host file  (127.0.0.1 <sitename>)

Now when i try to browse the file after providing the login credentials, i get the error:

"HTTP 500 Internal server error".

Please help me as I am stuck in my work.

Thanks in advance.