The captcha form located here: (http://guitarworkshopplus.com/?page_id=43) is showing up all broken to some windows users..
screen shot of broken form here: http://guitarworkshopplus.com/antispambox.jpg
It's most likely a theme conflict with the reCaptcha styles. What version of Windows is the problem visible in? Also, have you tried the form preview in the same browser to see if it happens there? If the preview page is fine then it's definitely going to be some CSS inheritance issue from your theme.