Delete that file manually (plugins_compiled_a03f0e39c594cdedf6c83893c9b9c3c8991f4cdf.dll) , and if it is not solved it is a problem of permissions: check the permissions of that folder, run TH as administrator or install it in another place that you have access
Regarding the thread theme, there are significant improvements. Also the first thing I thought was that now it would be easier to find pools xD