Hazak baruch, good questions. I have two big Stiras on Rav Shechter's analysis however. How do we know that having coffee near your computer is negligent in some way? this is problematic because firstly, isn't running in the hallways and classrooms even more negligent? I have been on more than one hatzolah call in schools where someone was running down a hallway, stairway etc. and got hurt, so really, which is pashut more mazik? I think the school also has rules about running in hallways so one can not simply say that only the one with Coffee is liable. Moreover, if it is very common and teachers also have a coffee mug with them, we wold not hold the teacher responsible, we would certainly say it was the student who was running around. I am sure as a rebbie you told a talmid or two in your day to slow down as well! Moreover, I do not think it is peshita negligent to have coffee near your computer. These days it is common. Most people have the cover and it is known that everyone has a coffee in their hand or desk or office cubical and I do not think we can create a takana today that someone with coffee near their desk is somehow a mazik. It has its dangers but clearly the one running through the halls has a much higher risk/damage liability and has far more answering to do. As for Ein Mevatlin on Kitniyot, does Ein Mevatlin apply to Kitniyot? Does it apply if the mixture is done before pesach? Ein Mevatlin is a derabanan concept and Kitniyot is certainly not a derabanan even for Ashkenazim. I think it is a far stretch especially if it is mevatel before pesach. In fact I remember answering shailas and calling a few kashrut organizations on the issue and I believe some Baby formulas have kitniyut and there were teshuvas to mix it with non kitniyut formula or potato starch before pesach. Granted its for babies, but still, Tzarich Iyun on that particular issue I think. Hazak Baruch

A possible explanation for R Schachter's opinion - Rochel could be considered a shoel as she is effectively borrowing the school's computer - or maybe even a socher as her parents paid tuition, so she might be considered to be hiring the computer. Regarding the issue of expanding the boundaries of nezek - everybody could be considered to have a lechatchila responsibility not to damage other people's property.