Correct, if you have PULSOUT generating a 100us pulse and an interrupt occurs while the pulse is being generated the actual pulsewidth will be "extended" for the duration of the interrupt. Bad, perhaps, but that's how interrupts work, they interrupt whatever the processor is doing (ie keeping track of time in order to generate a 100us wide pulse) and goes off doing something else, more important. If generating the 100us pulse is the most important/critical task then perhaps THAT should be done using interrupts.

/Henrik.