[Plugin: Really Simple CAPTCHA] Captcha images disappearing with WP 2.8.1

With my form, sometimes all 4 captcha characters show up just fine. Sometimes only 2 or 3 show up with the following error:

Warning: imagettftext() [function.imagettftext]: Could not read font in /nfs/c05/h01/mnt/69578/domains/eunicehart.com/html/wp-content/plugins/really-simple-captcha/really-simple-captcha.php on line 104

If I refresh, sometimes it works fine, sometimes it doesn’t. I am using WP 2.8.6 and I just downloaded Contact 7 and Really Simple Captcha today. Obviously have what is needed to show the captcha, it just doesn’t show up all of the time.

Has anyone been able to figure this out?

After update the captha disappearing in my order form

i have
* PHP Version: 5.2.6-1+lenny4
* System: Linux
* GD Support: Yes!
* GD Version: 2.0 or higher
* TTF Support (FreeType): Yes!
* JPEG Support: Yes!
* PNG Support: Yes!
* GIF Read Support: Yes!
* GIF Create Support: Yes!