Unable to browse to our Certificate Authority website certsrv

I am in the middle of renewing our Exchange certificate. When I browse to http://localhost/certserv, IE tells me that the website can't be displayed. More specifically, when I browse to that site via IIS, I receive the error below. My IIS expertice is limited so I don't want to start to change how the modules are handled etc without knowing exactly what I'm doing.
Thanks for your input!

Error Summary HTTP Error 500.0 - Internal Server Error The page cannot be displayed because an internal server error has occurred. Detailed Error InformationModule IsapiModule Notification ExecuteRequestHandler Handler AboMapperCustom-17386171 Error Code 0x800700c1 Requested URL http://192.168.**.**:80/CertSrv Physical Path C:\Windows\system32\CertSrv\en-US Logon Method Negotiate Logon User *******\*****