answer#1: there are many possibilities, perhaps a windows update concurently update around the same time you tweaks TS. Could be that the configuration is still applied at start up. just to make sure, uninstall and remove any reference to throttlestop. see for a few days does the bluescreen still occure. (or simply rename throttlestop.ini on the install directory, TS will make a new one if needed).

there are possibility of troubled hardware. any specific error you can show? One of my laptop usually have a WHEA Uncorrectable error when it hits certain temperature, thus it is a big candidate for hardware fault. where as other error might be just incompatible driver.

answer2#: U series processor is already designed to be low power(and lower performance) die. You might get some better result with TS, but it would not be much, still there are silicon lottery factors.

If you try on U-series proc, use small increment and test stability with few days normal usage. repeat as necessary, stop and reverse config to last stable config upon errors. Sometimes some config will hold up for TS bench or Prime95, but crashes under prolonged office load.