GM pranked:

General Motors Co. officials were red-faced on Wednesday after software on a network at its headquarters was programmed to insert a derogatory remark on computer browsers after any mention of Chrysler Group LLC and several competitors.

The prank came to light at GM's unveiling of a battery-powered version of its Chevrolet Spark small car at a five-day event marking the 100th anniversary of GM's Chevrolet brand. The event drew more than 200 journalists from around the world.

Selim Bingol, a GM spokesman, said the auto maker had nothing to do with the prank. GM has since corrected the problem. "This is not funny," he said.

GM officials said computer technicians found an unauthorized software program had been installed on a wireless router, and the program was altering the way Web pages were displayed to insert the word "sucks" after mention of some rivals on computers linked to the network.