A malfunctioning machine due to deliberate choices of the producing company, designer or the programmer.
The only thing that sends me into a blind rage is when the item in question doesn't work because of something stupid like a programmer taking an obvious shortcut or they omit a feature so that you must access their paid service or replace the product. It's not that I don't know how to fix it quite the opposite it's infuriating that I know what the problem is, know the end solution but I am blocked by the producer. I know what they did to hinder it and it irks me.
With everything else I am happy go lucky and easy going but ugh I hate working on badly designed machines especially electronics.