The human brain is an amazing organ. Despite our current technological expertise, it has yet to be equaled in terms of computing power per ounce, but it does have something in common with the hard drive on your computer:
Every time that you remember something, your brain re-commits it to memory, effectively playing post office with itself and fundamentally changing the memory. This has such a profound effect on your perceptions that it's actually possible to create memories of events that never happened, so vivid that your brain can't tell the difference.
Aside from how disturbing this is when applied to the idea of 'eyewitness testimony' at a trial, this has potentially destructive implications for your business. Even Customer Service and Salespeople that are 'young and sharp' remember things differently than they actually occurred.
How do you combat this? By making it part of your organization's culture to record everything in your CRM or database as soon as it happens (while it's happening, if possible, so that even the wording used is retained). If it was a phone conversation, record those and attach them to Customer accounts (in my call center experience, 95% of Customers remember a phone conversation differently than what actually occurred). If it was an email chain, make certain that those are attached to the Customer account, too.
The essential ingredient here is urgency. If a rep or anyone else who has direct communication with Customers is slow to record those communications, curb this behavior immediately. The longer anyone waits, the more that will become your culture, and the less accurate the information in your database will be. And then why are you spending so much money for it?