From what I remember about this error it has to do with the size of the menus.xml file. I think it may be only in DW8 and CS3 but this file can become too large and will not allow any more to be added when new extensions are installed.
The fix unfortunately would be to either try removing some of the extensions you have installed or delete your configuration folder which would have the effect of removing the installed extensions. If you install all of the same extensions again you will likely get the same error. Here is a link to a post about deleting the config folder: