Call waiting automatically connects caller to existing call

I have a major problem with Call Waiting. I can be speaking with someone, a call waiting notice comes on, I ignore it, and to my suprise.... the phone automatically answers and connects the person on call waiting to my phone call. All of the sudden I am in a 3-way call with no warning! Any ideas why this is happening or how to fix it? :confused:

That's scary and could cause problems....