Although later versions of Windows include the Windows Memory Diagnostic Tool, I highly recommend using Memtest86 instead. Memtest86 is a BIOS-based memory testing software, unlike other testing programs that must run within Windows. The benefit is that it allows you to test ALL of your memory for SESSION4_INITIALIZATION_FAILED errors, while other programs cannot test the section of memory occupied by the software itself, the operating system, and any other running programs.