The only warning I can give everyone out there, especially US residents where it is not legal, NEVER EVER PLUG YOUR PHONE LINE INTO YOUR DIRECTV RECEIVER WHILE YOU ARE USING ONE OF THESE CARDS. The reason is that is the only way they can detect a user. They can send a massive spike or zap through to try to knock people offline but if you do not have your phone line connected they have no way of knowing who is doing it. If you do connect your phone line it will provide them with a record of everything you have watched and bingo - you're busted. As for the frequency of being spiked. Usually it happens once or twice every month or two. There are random times where it might happen two or three times in a week but that is not all the time and there is usually a fix within 24 hrs. The only time I can't remember a quick fix is after the infamous "Black Sunday" episode the day of the Super Bowl in either 2000 or 2001 (I can't remember which year to be honest). DirecTV used a new spike that fried everyone's card. Had to switch to a different kind of card and it was a mess. Even then they had a fix within 1-2 weeks. That was the only significant problem that I've had in two years and I also have a friend who has had never had any other problems with it in over 4 years.
