I open a comms channel and it immediately starts sending the contents of a data file to the channel just opened. Why?
When a channel is closed, that is, the window to that channel is dismissed, if any logging actions were being carried out, those actions are not terminated until either (a) P2 is terminated or (b) you close them explicitly. To check for this, re-open the window and look at the file I/O indicators on the status bar.