It does not help me. Here is a path of source code from the comment page:
Security Code:<br>
<input name="publicKey" style="width: 90px;" maxlength="6" tabindex="5" class="textfield" type="text">
</td>
<td align="left" valign="bottom" width="100">
<img id="simple_captcha" src="https://192.168.1.100/wp-content/plugins/simple_captcha/gdimg.php?re=0" title="Simple CAPTCHA v1.2 by zorex" alt=""></td>
<td align="left" valign="bottom">
<img src="https://192.168.1.100/wp-content/plugins/simple_captcha/captcha_reload.gif" onclick="setTimeout('reloadCaptcha()', 300)" style="cursor: pointer;" title="Request a new image" alt="">
As a result i see this image
The directory permission 0755
