Hmm, I have other experiences...
I'm working with 0.99.96 and setting the spray disabled/enabled works very well for me. Also before spawning another particle object setting the rate of the original to zero works fine too.
The negative rate issue does not crash Construct, only the temp.exe, at least on my computer. It still needs to be corrected, just telling it to see if there are differences in Construct's behavior on different pc.