When you deleted the cache file, was Dreamweaver closed?
both DW and the extension manager must be closed when you delete the cache file.
try restarting the computer, then delete the cache.
if you continue to have problems, see the PM
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.