Just as a document created with a new version of a software cannot be read by the older version of the same software, extremely old documents sometimes cannot be read by the new versions of the software that initially created them. When this happens in a company such that the company cannot access its own aging data, the company is said to have corporate alzheimer's. The term was coined by chief open source officer Simon Phipps of Sun Microsystems while advocating the creation of a baseline standard for documents that would ensure that old data remains accessable.
Boss - "Johnson! I thought I told you to have the 1992 annual report on my desk this morning! Where is it?"
Scared but blameless employee - "Not my fault, sir. The document won't open cause it's too old. Looks like we've got corporate alzheimer's..."