Intuit's massive systems crash this week was complicated as efforts to solve one problem triggered more. And when the company restored power after its Internet-based services and systems went down, the restoration triggered a hardware failure. That explanation was made this week in a post by the company's chief information officer Ginny Lee.

"The process of restoring power caused a hardware system failure. We still don’t know the root cause of that," Lee wrote in her posts.

Although restored began immediately with the use of back-data, the company had to make sure there was "proper sequencing in a way where both individual applications and our own enterprise applications that they rely on are restored in the most reliable and secure way before bringing them back on line."