Hotels.com is warning nearly a quarter of a million customers that they may have had their credit card numbers stolen, following the theft of an unencrypted laptop belonging to the travel Web site's auditor, Ernst & Young Global.

The laptop was stolen in late February after an Ernst & Young employee left it inside a locked vehicle, according to Hotels.com Senior Compliance Officer Cathy Bump. Ernst & Young notified Hotels.com of the theft on May 3, and after determining which customers were affected by the data breach, the two companies began sending out letters last week notifying approximately 243,000 customers of the theft.

The laptop contained names, addresses, and credit or debit card information, mostly related to Hotels.com transactions that occurred in 2004, although some customers who made purchases in 2003 and 2002 were also affected.

The computer was stolen somewhere in Texas, though Bump would not name the city where the theft occurred. Hotels.com, which is owned by Expedia, is based in Dallas.

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