Marcos,
Heart monitor?
Hope you're OK. Have you been feeling bad, or is this just some kind of precautionary measure?
Funny thing about the check that Harrisdirect is asking you for...by the time they receive it, the trade will have been settled :/.
The three-day rule has been a funny animal online. While I do not abuse it, I have slid past it a couple of times (w/Ameritrade).
Difficult to say why some are targetted, unless one blatantly breaks the rule often, but the rule is gaining more observance.
Depending on how much you have in your account ($25,000, being the min.), will also affect how they treat you. Like Jake said, you could have been put on margin, but you also need a min. $ amt.
If you know someone by name at Harris, it may also be a good idea to remind them how long you have been with them, and you would hate to transfer your account (also mentioning you're part of a trading group = us). Sometimes, it helps.
Feel good, and let us know the outcome of both your endeavors.
See you with a strong heart, and possibly over at the Ameritrade trading desk.
~F8