help me

Well, my worst fear had once again reared it ugly head. For years, probably since grade school I have noted a form of 'Test Anxiety' which had spread to my public speaking.All throughout high school and college well into the current day have I noted a difficulty, almost a deafening. For years, whenever a Test would be given, my mind would go 'white', blank as a sheet of empty paper. Same situation occurs when I am about to present material that I know. In addition I get this overwhelming serge of numbness just prior to stepping up to the podium. I am usually confident until it is time and then what I know, practiced studying etc. would just disappear. No knowing what to stay, where to start.. even with a guide sheet or sides I would just stumble.. There has even been occasions while in meetings where I would begin a statement and fall off the radar and just lose what and where I was headed due to the thought of people thinking I am just off target. Just today, I was to present in front of about 50 people, knowing the material and also going so far as to write what I would say.. All gone once I was introduced. Help ME.. I was planning now to join Toastmasters in hopes, I can put a dent in this craziness.