Two US mobile operators have stopped selling Motorola's popular Razr phone after a batch of the handsets was found to be faulty.
The bug stops calls when the flip phone is opened up
The bug in the phones cuts off callers or makes the device shut down when the flip of the slimline handset is opened.
Cingular and T-Mobile pulled the phone off shop shelves while they work out which handsets belong to the bad batch.
Motorola said shipments of bug-free phones resumed on Monday, with the Razr due back in stores throughout the week.
The first slim Razr phones were introduced by Motorola in 2004 and since then have proved hugely popular. In results announced in mid-January Motorola said it had sold more than 12 million Razr handsets.
An early investigation by Motorola revealed that the bad batch of handsets was shipped to operators between 16 January and 28 February. The bug is known only to affect Razr handsets operating on GSM networks and has been traced to a faulty component in some gadgets.
On 6 March top US mobile operator Cingular stopped selling Razr handsets when it found out about the faulty phones. T-Mobile removed the handsets from its stores on 8 March.
It is not yet known if any Razr phones sold in the UK and Europe are in the bad batch.
"Motorola and its customers are addressing a quality issue affecting a very limited number of Razr handsets sold for GSM networks," said Motorola spokesman Alan Buddendeck in a written statement.
Motorola said it was not recalling any phones but would remove faulty phones from those delivered to operators. Both T-Mobile and Cingular said they hoped to put the phone back on sale in the US by 17 March at the latest.