Can't remove widgets

Hi. I have two DT theme widgets in my right sidebar – Button widget and Recent Listings – and they will not delete.
I click delete on the widget, the wheel spins – and that’s all it does.
I have disabled all plugins – apart from the Under construction plugin – although they were all disabled for a few minutes as a last ditch attempt to remove the widgets.
So, feel I have tried everything. Logged out, logged back in, used a different browser…
Any ideas?
Cheers,
Steve