I received a message from vcl.dialogs that sai=ys something about a criticalsection conflict (unfortunately I did not write down the message, and is hard to reproduce. It happend twice, then in a dozen trials doing the identical steps it did not show up).
I have a Tcriticalsection instance defined in one of my units and it is used in a thread, but it is always used in a acquaire/release pair in a try/finally block.
This happened in the IDE, where I have some breakpoints and I stopped the execution for several seconds.