I think this started sometime last week. Sometimes I get an error sign in the bottom address bar mainly on the main page of my board but sometimes in the different forums.
Your Bravenet counter at the bottom says that the code for the counter has changed, have you tried updating the code?
When i hit the delete it goes to the page that asks if you want to delete but when i click on the second delete sometimes it takes me to the main board. when it does this the post isn't being deleted.
Have you disabled "processing" screens on your board? If you currently have them disabled, if you enable them again, it should give the reason why you cannot delete a thread