I am very puzzled by the behavior you are seeing.
Obviously I am not encountering the same problems you are encountering.
You might try vary the delay of 900 useconds, since there are different pulse widhts.
Also you could try varying the IR command size, because there are differnet sizes, my remote is 21 bits.
I used this website to gather how the IR commands are encoded: Remote Control Technical Specifications
The behavior you are encountering is really puzzling, and unfortuanatly i can not think of a better solution.
youngrobot.