What is the Build number for your version of Dreamweaver?
Go to Help -> About Dreamweaver, when the about dialog box opens, click it once to force it to scroll to the end, this will show the version and build number. Please post back the build number.
If you could also post back a screen shot of the extension manager showing the installed extensions and version numbers, this would be helpful.
have you tried deleting the Dreamweaver cache file from the users configuration folder:
common_installation_issues.pdf