There is nothing wrong I can see with the page.
Maybe replace the & in the src with just an &
<img src="webassist/captcha/wavt_captchasecurityimages.php?field=Security_Code&noisefreq=15&noisecolor=060606&gridcolor=080808&font=fonts/MOM_T___.TTF&textcolor=040404" alt="Security Code" class="Captcha">
Could you put it up to a live location so I could view it? I think that may be necessary to debug any further.