The financial regulator has fined Nationwide Building Society almost £1m following the theft of a laptop from an employees home last year.
The computer contained confidential customer information and may have put millions at risk of identity theft.
The Financial Services Authority said Nationwide did not have adequate security procedures in place and was critical of the time it took to investigate.
Commenting on the fine, Nationwide apologised again to customers and said it had taken action to tighten its "already high security procedures".
We heard from some of Nationwide's angry customers and we spoke to Phil Jones, Assistant Commissioner at the Information Commissioner's Office.
The buy-to-let mortgage market is enjoying a boom according to new figures from the Council of Mortgage Lenders.
Buy-to-let performed stronger than the wider market, the CML said
Three hundred and thirty thousand buy-to-let mortgages were taken out in 2006 - up 48% on 2005.
But with interest rates rising three times in less than a year are new landlords putting themselves at risk?
We asked Gus Park, head of buy-to-let for Bradford and Bingley, and spoke to John Socha of the National Landlords Association.
Adult financial education
Many people struggle to find the time or motivation to evaluate their personal finances but now some employers are giving their staff the chance to do just that - on company time.
The FSA aims to help consumers manage their money better
The sessions are part of a £10m Financial Services Authority scheme to give hundreds of thousands of employees the opportunity to find out more about managing their money.
Bob Howard reported.
More and more people are choosing to live together without getting married but unmarried couples have few legal rights.
Unmarried couples who live together have few legal rights
We heard from one Money Box listener keen find a way to safeguard her son's rights and asked Jane Craig, a partner at law firm Manches what people in this situation can do.
Capital One has been fined £175,000 by the financial regulator as part of its crackdown over payment protection insurance.
And the Office of Fair Trading is calling on the Banking Codes Review to raise the standards of fairness in the way banks treat their customers.
BBC Radio 4's Money Box was broadcast on Saturday, 17 February 2007 at 1204 GMT.
The programme was repeated on Sunday, 18 February at 2102 GMT.