I'm sorry to hear about the difficulties you are experiencing.
The Auctiva Uploader uses Java so I suspect the message you are receiving is indicative that you do not have the required Java plugin installed, or that there is an issue with the plug-in. If you simply do not have this Java plug-in installed, you should just need to install the plug-in when prompted to be able to use the uploader.
On the other hand, if you were previously able to use the Auctiva Uploader successfully and therefore already have the required Java plug-in installed, the behavior you are seeing is likely a side effect of the latest Java update (version 7 update 51) that was released.
This particular Java update caused a variety of uploading difficulties for our users - including though who have not installed the update - so, in that case, I recommend checking to make sure you have the latest version of Java installed.
You can confirm whether you are using the latest version of Java (and update if applicable) from the following page of the Java website: www.java.com/verify
If you have already installed the latest version of Java, or you continue to encounter the same behavior after updating, please contact our Customer Support team directly from under the “Help” tab on our site and we will be happy to continue working with you on this.