PDF Form HTTP Submit in Adobe Reader

I have some PDF forms i wish to distribute and to make my lfe easier i want to collect the responses via an HTTP Submit button on the page.

This in it's self is no problem and took about 10 minutes to make, it works fine in Acrobat Pro, but i ran into a problem in Adobe Reader.

This seems to be an old problem since i am finding people asking about it going back years, adobe reader keeps returning "Cannot handle content type: text/html;"  this is because it can't dispay a webpage.

Suggested solutions i have found on teh net are as follows:

Having IE open will cause a new window to spawn and the error won't occur, but i can't guarantee IE will be open.

Return a PDF as the response is another common solution which i have tried with the following:
<code>
header('Content-type: application/pdf');
header('Content-Disposition: attachment;filename="/thankyou.pdf"');
</code>
this works in a browser but not in adobe reader

Return a status code which tells it not to expect any data
<code>
header('Status: 204 No Content');
</code>
This still produces the same error

I have tried sending back some hand wrtten FDF but that is still producing the same error.

So in short regardless of the headers i specify it is seeing it as "text/html".

All i really want is for the error to go away, the ultimate solution would be to cause a pop-up message where i can give some feedback.

If anyone could give a working example of some code that accepts posted data from a pdf and sends a response that doesn't error in adobe reader (only looking to support ver 7+) it would be greatly appreciated.