Christopher Stanford, a state fire marshal investigator, said the house fire at 117 Granite Street in Biddeford last Monday began about 8:30 a.m. after the owners used the computer, then left it plugged in to charge while they went to work. The Dell Inspiron 1200 apparently "had something happen with the cord or the power unit on the cord," Stanford said, because the damage was most severe where the laptop and cord were located in the house.

"That was the only thing we had in terms of a heat source," Stanford said. Fire officials ruled out other potential causes or arson.

"The couch was totally burned out and the laptop was still sitting on what remained of the sofa" when Stanford conducted his investigation. No one was home at the time of the fire. The single-family detached house, which was about 130 years old, was a total loss with damage estimated at more than US$100,000, Stanford said.

It was the second house fire caused by a laptop in the area since last summer, when a Compaq laptop erupted in flames and destroyed another home, he said.

A spokesperson for Dell Inc. in Austin, Texas, could not be reached for comment. The owners of the home also could not be reached.