Submit Form Error

I have recently moved many previously working websites
over from a shared Linux hosting environment to a
dedicated Windows 2003 server and I am having issues with
my FrontPage forms.

When trying to submit a previously working from I keep
getting the following error message:

--------------------------------------------------------
FrontPage Error.
User: please report details to this site's webmaster.
Webmaster: please see the server's application log for
more details.
--------------------------------------------------------
There are no event errors logged to view.
I can successfully publish the site so it appears to be
just a form issue.

I have done the following to try and resolve this:

1. Verified the SMTP mail settings in IIS for this website
are correct.
2. Used the name server mail server:
mail.nameserverdomain.net
3. Used the site mail server: mail.clientwebiste.com
4. Tried the IP address for the mail server.
5. The 'From' & 'Reply-To' email addresses are valid
working accounts.
6. I have also uninstalled and re-installed the server
extensions for the entire server as well as the specific
site.