If you are referring to the default install WebSignup snippet, the default template is in assets/snippets/weblogin/websignup.inc.php, on lines 175 - 495.
If you simply call the snippet like so: [!WebSignup!], it will show using the default template. The optional configuration parameters which can be passed to the snippet are listed in the top of the snippet code (edit the snippet to see them) for reference.
[[WebSignup? &tpl=`signupTpl`]]
<!-- #declare:separator <hr> -->
<!-- login form section-->
<form id="commentform" method="post" name="websignupfrm" action="[+action+]">
<div><label for="username">Username<span class="required">*</span></label>
<div class="outerborder"><input type="text" name="username" maxlength="15" value="[+username+]"></div></div>
<div><label for="fullname">Full Name<span class="required">*</span></label>
<div class="outerborder"><input type="text" name="fullname" maxlength="100" value="[+fullname+]"></div></div>
<div><label for="email">Email<span class="required">*</span></label>
<div class="outerborder"><input type="text" name="email" value="[+email+]"></div></div>
<div><label for="password">Password<span class="required">*</span></label>
<div class="outerborder"><input type="password" name="password"></div></div>
<div><label for="confirmpassword">Confirm Password<span class="required">*</span></label>
<div class="outerborder"><input type="password" name="confirmpassword"></div></div>
<div class="signupcaptcha"><?php if ($useCaptcha){ ?>
<a href="[+action+]"><img align="top" src="manager/includes/veriword.php?rand=<?php echo rand(); ?>" width="148" height="60" alt="If you have trouble reading the code, click on the code itself to generate a new random code."></a>
<?php } ?></div>
<div><label for="formcode">Form Code<span class="required">*</span></label>
<div class="outerborder"> <input type="text" name="formcode"></div></div>
<div id="sendbutton" class="clear"><input type="submit" name="cmdwebsignup" id="submit" class="button" value="Send" /></div>
</form>
<hr>
<!-- notification section -->
<span style="font-weight:bold;">Signup completed successfully</span><br />
Your account was successfully created.<br />
A copy of your signup information was sent to your email address.<br /><br />
First maybe try calling the snippet uncached: [!WebSignup!]
If that doesn’t change anything, next try taking the captcha part out of your template, I know there is sometimes issues with it (as well as the <?php code in that section of the template that may be causing the conflict).