hi Jo Ann,
I cleaned my html code of the form up:
I get two errors in dreamweaver's W3C validation:
An attribute value must be a literal unless it contains only name characters...
and also: "document type does not allow element "a" here"
could that be the problem? but I don't know where to look at (should be at line nr 3!)

<div style="max-width: 400px">
<script type="text/javascript">
document.write(unescape("iframe id=\"fb_iframe\" src=\"contact-All-Con.php" + window.location.search + "\" width=\"100%\" height=\"981\"allowtransparency=\"true\" scrolling=\"no\" frameborder=\"0\"<a href=\"contact-All-Con.php\" title=\"contact-All-Con\">Check out my CoffeeCup Form</a>iframe"));</script>
<noscript>
<iframe width="100%" height="981" style="border:none; background:transparent; overflow:hidden;" id="fb_iframe" src="contact-All-Con/contact-All-Con.html">
<a href="contact-All-Con.php" title="contact-All-Con">Check
out my CoffeeCup Form</a>
</iframe>
</noscript>
</div>

I would open a support ticket for that error Piet, could be CC doesn't realize it's giving that error, or they should be able to help you track down why you're getting it if something else is wrong.

OK thanks for all your help and time!
fingers crossed ;-)