Thank you very much. But my case, I can't find the cache file name MacFileCachexxxxxx.dat. It's weird but seems like my Configuration folder is not in a good condition.
My solution is to reinstall every extensions. The fastest way without waiting a night to uninstall extensions on Mac is .....
1. Close every Adobe app.
2. Rename "~/Library/Application Support/Adobe/Dreamweaver CS4/" folder
3. Open Dreamweaver CS4 again and it'll create the new Blank folder, then quit
4. Open Extension Manager CS4 again, it'll have no extensions at all.
5. Reinstall each extension, by release date if possible to find.
6. Viola! My problem is gone!
Not a good solution but work for me right now.