Microsoft laid off 1400 employees in January and gave them a severance package. Unfortunately someone made a mistake and miscalculated the amount of payment. Some people were underpaid and some were overpaid. The people who were overpaid got a letter from Microsoft requesting a return of the overpayment. They threaten to sue the people who don't send the money back. The article doesn't mention how quickly Microsoft will pay the people they under compensated.
I agree that, ethically, the people are obligated to return any overpayment. And, most likely, they signed papers agreeing to the severance terms and are bound by that. On the other hand, I'd love to know the total amount of the overpayment. If the amount is less than a million or so, I think Microsoft might have been better off forgetting the whole thing. Partly because the public sympathizes with the newly unemployed people and partly because Microsoft has to admit they made a mistake even though they make software that should have helped with the calculations. Just put the formula in Excel and let it do the math.
Also, what do you want to bet that at least one of the unemployed will sue Microsoft claiming undue distress caused by the lay off and then the letter demanding return of the money. So Microsoft will be out a bundle anyway and might as well have just let the laid off employees keep it rather than spend it on lawyers.
UPDATED: Microsoft decided to let the people keep the extra money. With about 25 people getting up to $5,000 extra, the overpayment cost MS $125,000.