Well, the code hasn't been changed in quite some time and it was working on another server (FreeBSD based) so I don't think that's it. Also, it passes the W3C validator. Here's the code for the form page:
<?php include("0header.php"); ?>
<h1 align="center">Request a quote</h1>
<p>Please fill in as much of the following form as possible. The more information
we have about your project, the more accurately we can quote. You must
include some way for us to contact you. Fields marked with * are required.</p>
<p align="center"><font color="#FF0000">**** PLEASE NOTE: We have had reports
that this form isn't working - please follow-up with a phone call to make
sure your request was received ****</font> </p>
<form name="form1" method="post" action="quotefm.php">
<div id="main">
<input type="hidden" name="require" value="email,phone_no,cust_name,description" />
<input type=hidden name="subject" value="WWW Quote Request" />
<input type=hidden name="redirect" value="http://www.leesburgsign.com/quoteok.php" />
<table>
<tr>
<td colspan="2"><div align="center"><strong><em>Customer info</em></strong></div></td>
</tr>
<tr>
<td width="203">Your name:*</td>
<td width="669"><input name="cust_name" type=text size="80" /></td>
</tr>
<tr>
<td>Your telephone:*</td>
<td><input name="phone_no" type=text size="22" /></td>
</tr>
<tr>
<td>Your fax:</td>
<td><input name="fax_no" type=text size="22" /></td>
</tr>
<tr>
<td>Your e-mail:*</td>
<td><input name="email" type=text size="80" /></td>
</tr>
<tr>
<td>Your address:</td>
<td><input name="ship_to" type=text size="80" /></td>
</tr>
<tr>
<td>Your city:</td>
<td><input name="ship_city" type=text size="80" /></td>
</tr>
<tr>
<td>Your state:</td>
<td><select name="ship_state" size="1">
<option value="AL">Alabama</option>
<option value="AK">Alaska</option>
<option value="AZ">Arizona</option>
<option value="AR">Arkansas</option>
<option value="CA">California</option>
<option value="CO">Colorado</option>
<option value="CT">Connecticut</option>
<option value="DE">Delaware</option>
<option value="DC">Dist of Columbia</option>
<option value="FL">Florida</option>
<option value="GA">Georgia</option>
<option value="HI">Hawaii</option>
<option value="ID">Idaho</option>
<option value="IL">Illinois</option>
<option value="IN">Indiana</option>
<option value="IA">Iowa</option>
<option value="KS">Kansas</option>
<option value="KY">Kentucky</option>
<option value="LA">Louisiana</option>
<option value="ME">Maine</option>
<option value="MD">Maryland</option>
<option value="MA">Massachusetts</option>
<option value="MI">Michigan</option>
<option value="MN">Minnesota</option>
<option value="MS">Mississippi</option>
<option value="MO">Missouri</option>
<option value="MT">Montana</option>
<option value="NE">Nebraska</option>
<option value="NV">Nevada</option>
<option value="NH">New Hampshire</option>
<option value="NJ">New Jersey</option>
<option value="NM">New Mexico</option>
<option value="NY">New York</option>
<option value="NC">North Carolina</option>
<option value="ND">North Dakota</option>
<option value="OH">Ohio</option>
<option value="OK">Oklahoma</option>
<option value="OR">Oregon</option>
<option value="PA">Pennsylvania</option>
<option value="RI">Rhode Island</option>
<option value="SC">South Carolina</option>
<option value="SD">South Dakota</option>
<option value="TN">Tennessee</option>
<option value="TX">Texas</option>
<option value="UT">Utah</option>
<option value="VT">Vermont</option>
<option value="VA">Virginia</option>
<option value="WA">Washington</option>
<option value="WV">West Virginia</option>
<option value="WI">Wisconsin</option>
<option value="WY">Wyoming</option>
</select></td>
</tr>
<tr>
<td>Your zipcode:</td>
<td><input name="zip_code" type=text size="20" maxlength="10" /></td>
</tr>
<tr>
<td colspan="2"><div align="center"><strong><em>Quote details</em></strong></div></td>
</tr>
<tr>
<td>Please describe project in as much detail as possible:*</td>
<td><textarea name="description" cols="80" rows="7"></textarea></td>
</tr>
<tr>
<td>To prevent spam-bots, please enter the number you see in the box.</td>
<td><img src="images/nospam.png" width="160" height="33" /> --->
<input name="nospam" type=text size="20" maxlength="10" /></td>
</tr>
<tr>
<td colspan="2"><input type="submit" value="Request Quote" />
<input type="reset" /></td>
</tr>
</table>
</div>
</form>
<?php include("0footer.php"); ?>