Pulse Generation and Pulse Removal

[chall]

I have a PXI-5422 and would like to generate an inverted pulse that is about two and a half milliseconds across and only pulses one time.  I have been modifying the "Fgen Arbitrary Waveform.vi"  I seem to have two problems with it.

The first problem that I have is that a pulse seems to be generated by the device without being specified.  When I use the example with no modification and specify a sine wave, I get something that looks like the attached picture.  There is an unwanted pulse followed by sine wave generation.  So my question is how do I get rid of this initial pulse?  What is actually causing that pulse, since it does not seem to be specified in the data array being passed to it?

My second question is how do I get it to send out only one discrete pulse and stop generating.  I assumed all that I would need to do is remove the while loops in the example and send my own array of data with a pulse.  When I do this I still get the preliminary pulse that I doesn't match my pulse requirements, then I will often get a waveform that goes up and down several times, perhaps this comes from running the vi consecutively too fast?  The pulse does come out looking just as I anticipated some of the time, so I'm confident that my specifications are fine.  And with the while loops in place they are crisp and nice.

Thanks in advance!