I'm having a reliability issue with an URC MSC-400 and was hoping one of the more advanced users could give me some pointers.

I have a few serial devices I've created and then I generated the smartMacros. I then use an MX-900 remote to trigger the RS232 smartMacros.

Problem:
When you press the same button over and over about 1/10 presses fail to result in an RS232 string being sent from the MSC-400.

What I know:
No RF interference according to the RFX-250 red light.
Blue light on the MSC-400 indicates receipt of RF transmission for 10/10 presses.
I've verified the symptoms in hyperterminal (serial port properties match).
I've used live update to update to the newest MSC-400 editor.
I'm not using any delays, should I be?

Other notes:
What's even stranger is that if I go and alternate button presses, say I press UP then DOWN as fast as I can on the remote, every RS232 command is received successfully (verified in hyperterminal)! This by itself tells me my remote buttons are working and that there is no RS232 cable issue.