TaskHost.exe itself is a wrapper for dll or other exe and run as a windows service.
3 things to try
#1
Before spending time hunting down what taskhost actual loaded. Check Event Viewer for errors. That may give out a quick answer or point you to the right direction.
#2
Open Task Manager, go to Processes tab. On menu bar (top), click View -> Select Columns.... In pop-up windows, select Command Line.
That may give you an idea which dll taskhost.exe loaded.
Additionally, pay attention at the path of taskhost.exe. It should be
<Windows directory>\System32\Taskhost.exe
If not, you may have other problem.
#3
Same idea as #2, but use a better tools. Download Process Explorer from Microsoft. It is free. It is able to give more details of running process.