Wordpress 2.8.3 upgrade or downgrade of 2.8.2?

I was so impressed with the latest 2.8.2 that I had to tell the world Wordpress 2.8.2 is a masterpiece. So I just clicked on the 2.8.3 version upgrade and I did not realize and good change. Now I realize some bad changes. I want to delete a plugin and wordpress tells me that it was deleted but it’s still there. Even from FTP I’m not able to delete the plugin directory. Some plugins are deactivate and when I want to activate them Wordpress tells me that the plugin files are not found, so I want to delete the plugin but Wordpress keeps telling me that the plugin files are not found. I go to my FTP client and want to delete the plugin which I cannot. Somone plz?