[Q] Execution of PHP from <form action>

I am running the latest DW version on my local system on which Apache and MySQL
are installed. My system is Windows XP based.

The PHP script, invoked by the action parameter (see html, below), is not
executed. Instead, the script's source is displayed in the target frame. My
Apache-PHP installation is correct because I can execute the script on my
system by passing
'http://localhost/my/root/folder/scripts/update_river_measurements.php' to
IExplore on the command line. What's happening is that DW seems unable to do
this.

Finally, I'm pretty sure I have correctly configured my testing server
([site]->[edit sites].

Any suggestions as to what I might try would be greatly appreciated.

Cheers,

Michael
=================== HTML code below ===========================

<form action="update_river_measurements.php" method="post" name="form1"
target="mainFrame">
<select name="interval_period">
<option>Select interval</option>
<option value="2">2 days</option>
<option value="4">4 days</option>
<option value="8">8 days</option>
<option value="31">31 days</option>
</select>
<input type="submit" value="Update Database">
</form>

One final point: When I upload these pages to my remote host, the form and the PHP script execute perfectly. So, the problem is with the way I've configured DW.

Thanks,

Michael