sorry to hear that you had a bad experience with visualCaptcha :(
The visual part of the plugin uses wordpress pre-installed scripts so if you have a problem with that it means that you have an issue else where on your wordpress site. Using this pre-installed scripts is a mandatory point for wordpress.org and visualCaptcha complies with it. So, any problem there really means a problem on wordpress.
Usually this issue its associated with a template or a plugin that is forcing a different version of a javascrip library (jQuery or jQuery UI). Do you have a custom template for your admin or do you some sort of customized part on your wp-admin page?
I would like to point out that this is the first time that someone reports this type of behavior on visualCaptcha for WordPress. That is why there is no mention to this anywhere else on the web.
WordPress.org creates a support page for each and everyone of the plugins they distribute. In case of problems you should first look there and then contact the plugin developers for assistance. I would gladly help you trying to understand what is the problem with your WordPress site but for that to happen all you have to do is contact us through the support area:
Once again I'm sorry for any inconvenience this may have caused you and I would like to help you understand what went wrong.