Java - web site's certificate cannot be verified.

Our company uses for training. Some of the presentations are using Java and we always get a certificate error when they are launched. I don’t notice these errors when accessing a presentation that is web based. Is there something that needs to be done on the java client so that the certificate is trusted? We are using the latest version of the Java client.

The web site’s certificate cannot be verified. Do you want to continue?
The certificate was issued by a source that is not trusted.

Any suggestions would be greatly appricated!