I am hoping that whatever technical support person reads this topic can help me as well.
I encounter exactly the same error message when I try to open SiteAssist Pro:
I have run a search through this forum and read all (all!) of the information previously posted on this topic, and have tried the solutions given (deleting cache file, deleting configuration folder, de/re-installing Dreamweaver and its extensions), in every possible combination of sequencing of reinstallation, deletion, restarting, opening, etc. I have reached the limit of what I can attempt by myself - I'd like to get a tech support ticket or some other intervention to solve this problem.
I am using Mac OSX and Dreamweaver CS4.