If you have uninstalled and re-installed then you should have removed any existing issues that may have been present initially. Have you also tried deleting the cache file or the configuration folder to see if there is an issue with either of these?
To clear the cache file please take a look at this thread, it gives details on clearing this file to help resolve issues that are related to it:
Here is also a link to a post about the configuration folder if clearing the cache does not work for you:
Please try these things to see if it helps to clear up the issue. Also what is the version of DW you are working with and the build? There is a known issue in DW8 build 3453 that will result in a similar error about the floater.