It sounds as though you still have a corrupted cache file. This is often caused by incompatible extensions. Disable all extensions that you have installed in Dreamweaver, and delete the cache file again. Relaunch Dreamweaver and try using the form wizard again. If it works OK, you can start enabling your extensions again one at a time. As soon as the problem returns, you know you have found the extension responsible for the problem.
Another possibility, but less likely, is that you need to delete your personal configuration folder. Details of how to find the folder are in the Dreamweaver FAQ.