It looks like – for some reason – that the plugin can't set & save it's basic/default settings to the WP options database.
The reason you see this message is due to the form count being 0, whereas when activating the plugin it should be set to 1 (for the default form).
Can you access yor WP tables directly? You could check if any cforms_* entries exist in your wp_options table…which I doubt, just based on what you're seeing.
Unfortunately, I have not a clue as to why your implementation of WP is not letting cforms write to its tables…
I don't know too much about MySQL but I don't think there's anything special there.
Other plugins work OK. (Akisme, Event Calendar, Math Comment Spam Protection, WP-dTree, WP-Scriptaculous and wpPHPMailer)
No special wp-config
<?php
// ** MySQL settings ** //
define('DB_NAME', 'wordpress'); // The name of the database
define('DB_USER', '****'); // Your MySQL username
define('DB_PASSWORD', '****'); // …and password
define('DB_HOST', 'localhost'); // 99% chance you won't need to change this value
// You can have multiple installations in one database if you give each a unique prefix
$table_prefix = 'wp_'; // Only numbers, letters, and underscores please!
// Change this to localize WordPress. A corresponding MO file for the
// chosen language must be installed to wp-includes/languages.
// For example, install de.mo to wp-includes/languages and set WPLANG to 'de'
// to enable German language support.
define ('WPLANG', 'us');
OK, I just logged on to WP admin on the server itself and it worked fine so it must be something in our firewall (maybe) but anyways, it works and I'm narrowing down the problems.
Sorry I can't be of much help, but neither have I any experience with IIS nor have I ever run into issues with web servers complaining about cforms.
If you've turned on DB Tracking and use attachments, check writing permissions on the upload directory.
Also, quickly google'ing I found this link, excerpt:
Cause
The file type is not registered in the IIS script map settings (e.g. .html or .htm). IIS 5.1 only allows HTTP requests of type to GET to unmapped files. HTTP requests of type POST, HEAD, and all others are responded to with a 405 resource not allowed error.
As a security note, you should always remove unused script mappings. This is the default behavior of IIS 6, which will only serve named extensions and refuse all others.
Resolution
Add a script map for the extension. A script map associates a particular file type with a given script module. The web server runs the module on the given file and sends the output to the browser, instead of sending the file directly to the browser.
Go to "Control Panel"-"Administrative Tools"-"Internet Information Services".
Expand the tree to "COMPUTERNAME"-"Web Sites"-"Default Web Site".
Right-click on "Default Web Site" and select "Properties". (Alternately, select "Default Web Site" and press Alt+Enter.)
Select the "Home Directory" tab.
Click the "Configuration" button.
From the "Mappings" tab, select the "Add" button.
Click the "Browse…" button, choose "Dynamic Link Libraries *.dll" from the "Files of Type" dropdown, and select c:\\WINDOWS\\System32\\inetsrv\\asp.dll.
Type ".html" (without quotes) in the "Extension" box.
Select the "Limit to:" radio button, and type in "GET, POST" (without quotes) in the box next to it.
Click the "OK" button and close all the dialogs. (If the "OK" button is greyed out, then make sure all the entries are correct and try clicking in the file name box.)
See the screen shot below. You must adjust the above instructions to your particular OS, web site configuration, and file type. You can associate the file type with a different script engine besides asp.dll, which is the ASP 3.0 script engine. There is no need to give IWAM_COMPUTERNAME permission to the file, only IUSR_COMPUTERNAME needs NTFS read and execute permission.
The only reason for why this appears is non existing form count setting (in wp_options: cforms_formcount).
During activation and if no cforms data is available, the plugin starts from scratch and creates a first set of data (with default form), including the above setting.
have you had cforms installed and working earlier?
can you access your wp_options (via DB admin tools) table in your WP installation to see if any 'cforms_…' option has been set ?
is there anything special about your WP/server that would not allow a plugin to write to wp_options?