US wireless carrier AT&T is facing more criticism, as some users report that after logging in to the company's web site using their own username and password, they were redirected to someone else's account.
In a statement to tech blog Gizmodo, AT&T said it was unable to home in on the problem, but reassured users that sensitive information such as social security and credit card numbers had not been revealed.
Gizmodo also received a letter from an AT&T insider claiming that the problems were related to a failed AT&T server software update last weekend.
The insider wrote: "Over the weekend there was a major fraud update that went down on all of AT&T's systems, from Saturday overnight to Sunday early morning. All systems were down and agents were unable to use any systems. The issues people are seeing at AT&T stores and online are most likely related to this update that went wrong."
Some users reported that once they had refreshed the page containing another user's information, they were directed back to their own page.
This latest hiccup comes after AT&T confirmed that its website was having problems in coping with the overwhelming number of iPhone 4 pre-orders placed by Apple fans.