The message "Windows protection error. You need to restart your computer." is the default message Windows 9x/ME displays when a fatal error occurs. As such it can be result of a lot of different errors Windows might encounter, even ones not involving any sort hardware protection being violated. It can happen, for example, when Windows can't allocate a critical data structure. It's not usually displayed when a program tries to access memory it shouldn't, as this normally isn't a fatal error and only results in the process being killed.