When I first heard about the thing with TD Ameritrade, I placed a small order through Scottrade and noticed everything was fine. It still is with Scottrade.
It appears to be something only occurring with TD Ameritrade.
Since I do some bottom fishing in penny land, I had a similar experience with Scottrade. It had to do with algorithms and their tracking of computer trading patterns. They electronically monitor trading patterns and will sometimes put in place a hold, especially in penny stocks. My hold came from Scottrade only.
No hold from Scottrade with SSOL