restart the OS,
then follow step 12 of the Adobe troubleshooting guide to recreate the users configuration folder:
Once the configuration folder has been renamed, go to the web assist site to download the extensions. when downloading, make sure to select the option to save the files. if you are prompted to open, select no and save instead.
After downloading, open the extension manager, click the install button and browse to the downloaded extension files to start the install.