Raymond Chen on more herculean efforts to retain backward compatibility in Windows, this time related to virtual memory management:

In Windows†95, the memory manager was completely rewritten and the above coincidence was no longer true. To conserve kernel-mode virtual address space, physical memory was now mapped linearly only as necessary. Of course, the drivers that relied on the old behavior were now broken because the undocumented behavior they relied upon was no longer present. As a result, when it starts up, Windows†95 looks around to see if any drivers known to rely on this undocumented behavior are loaded.

Wow. (Pun intended.)