To be exact about your system information, always post the results of MyEclipse > Installation Summary > Installation Details for us. Also, provide a code example of where you are invoking autocomplete, it’s possible that you are invoking it in a location that it’s not supported.
And lastly, check your log file (<workspace dir>\.metadata\.log) for exceptions near the bottom that would explain in more detail what the NPE is comming from.
When you get a chance have a look at our [URL=http://www.myeclipseide.com/PNphpBB2+file-viewtopic-t-393.html]Posting Guidelines[/URL] just for a quick reference on what we need when you post.