I can empathize with what you are saying as I work in the trade myself, its full of deadlines where you need things to work and not fux up on you in the middle of work but i've also been at the recieving end a lot of times where one little windows (forced)autoupdate or a new driver can cost days of head scratching and angry phone calls and I can relate to that.
My first thought is always "could this be an autoupdate issue", but yes I totally agree a stacktrace analysis is the correct way to continue after your initial conversation & checks proves fruitless.
Ive personally seen it, a lot of smaller companys dont have the manpower to spend much time with each customer seperately and will take the "blame the other guy first mentality" not personal, but not knowing their skill level and will have them go through what can sometimes seem unhelpfull and patronising to some, before putting resources into a solution, I think the guys at Scirra were just following a similar approach.
Best of luck with your projects.
btw I didnt think you were rude, just sounded like you were shouting a bit, lol.