As this error came back two times right after reboot as well I investigated further.
I created a new SQL Window and entered there
(including a new line). Then I recorded a macro with the following code, including Ctrl+C/Ctrl+V:
Move cursor to beginning of line
Move cursor and select to end of line
Copy selection to clipboard
Move cursor to end of line
Break line at current position, move caret to new line
Paste clipboard to current position
Copy/Paste using Ctrl+C/Ctrl+V didn't work while recording the macro, but as the code shows, the commands were all recognized correctly! Now when I go back to my select line and playback the recorded macro I get an error window in PSD "Cannot open clipboard"! When I recorded and playbacked the same macro in a healthy PSD session, it does what is expected and copies my select line to the next line. I hope this helps getting this error finally sorted out!
Another discovery in the messed up PSD session: When I start in the 2nd line (the empty one) I don't get an error and it creates another empty 3rd line. Using macro playback again there I get an empty 4th line and so on.
Analyzing the behaviour using
http://freeclipboardviewer.com/ shows that a clipboard entry does get generated even when getting the error, however without any valid content.
Even in messed-up mode sometimes when using Ctrl-C repeatedly, the line does get stored in clipboard correctly. This happens randomly between about every 5th to about every 40th time in my case.
The problem is clearly with Copy (Ctrl+C). When a selection gets successfully copied to the Clipboard, then Paste (Ctrl+V) works fine too. When using the menu otpins Edit - Copy (Alt E, Alt C) the behaviour is just the same.
When I execute my query, select then my output grid, the Ctrl-C copies the output correctly all the time, even in messed up mode. However when I created some output using dbms_output package and try using Ctrl-C there, it show the same messed-up behaviour.
