Hello,
Thank you for your message.
This seems to be rather server configuration issue, not a development issue.
At first, please try to find as much as possible about this error in your web server event log, if you have access to it.
Then, also please check if your virtual directory and IIS are configured according to instructions from DevGuide, e.g. at
Creating a virtual directory and optionally
IIS configuration on Win 7 or 2008 R2Does your hosting provider give any requirements/restrictions for the web.config file?
Regards,
Zdenek C.