Fixing the error "An operations error occured." in an asp.net application using Active Directory.

Hello

I have a asp.net web application which uses forms authentication which connects to Active Directory to authenciate users.  

Having installed the system on site.  I recieve the following error message when trying to connect to Active Directory.  

"An operations error occured."

I have searched on google and found severeal causes/solutions.  So far I have had no luck!  
My knowledge of Active Directory is very limited.

Any advice would be great :)