I also had seen one or two instances of the Black Tab Bug on the DCS Desktop with PG. At the time didn't know about the ALT-F4 trick. Yesterday I installed both a Zone Alarm Upgrade, and all the Windows Patchs appropriate for my version of XP Pro. Last night while experimenting with something else I noticed that now the Black Tab Bug is no longer intermittment but is appears everytime Process Guard blocks something. ALT F4 does work, Process Guard does block the program from executing, and I can go into Process Guard, and make appropriate changes, but wonder if anyone else noticed this. Regrettably I did both upgrades before noticing. However since the ZA upgrade was really very minor, and since the problem was there before, I suspect the real culprit is the windows upgrades.