Are you sure that you deleted the preferences folder properly? Even check in Task Manager to see that LW's properly closed. And you changed compatibility?
Did you try reinstalling LW using it's offline installer? The online (recommended) one can cause problems.

Are you using any antispyware/security programs that might be seeing LW as a threat & not letting it open? Make sure LW's on the list of exceptions/allowed apps list of any security programs you're using.