Well, I've figured it out why the Shortcut Ctrl+Shift+I, which should be inverse the selection, doesn't work! If I have ICQ 6 Messenger running in background, the shortcut is not working. The final reason for me about the problem is that the ICQ 6 Messenger is stealing the key combination. And @chrisjbirchall, you were right about the process that is "stealing" the combination. Thanks a lot!