A Greater Manchester council has lost details of 200 disabled residents - a year after a previous security blunder.
Wigan Council believes a memory stick containing hundreds of confidential details fell out of an employee's pocket in January.
A laptop computer with information about 33,000 local children was stolen from council offices in January 2009.
Town hall chiefs have suspended one member of staff and disciplined another in relation to the latest loss.
Officials from the Adult Services department have spent the last two days individually contacting each of the 200 disabled residents to explain what happened.
The personal details saved on the memory stick include names, addresses, some national insurance numbers, ethnicity and types of disability, but no financial data was lost.
The laptop computer containing the information about the thousands of local children which was stolen last year has never been recovered, a council spokeswoman confirmed.
Bernard Walker, executive director of health and wellbeing, sent a letter out to all members of the council stating there was a "complete ban" on the use of memory sticks and pen drives for any purpose until a long term solution is identified.
In the letter he said: "Clearly the council will apologise to the individuals concerned and express regret.
"It is believed, however, that the council has not acted unreasonably in attempting to secure this information and all relevant actions are being taken to prevent any further loss.
"The staff concerned were acting in breach of the council's policies in using the memory stick for this information and a disciplinary investigation is being carried out."
Any remaining memory sticks with confidential details will be encrypted and all laptops, including councillor's own laptops, will also be locked with a password.