CNN said yesterday that a technical glitch caused a large, black X to appear briefly over the image of Vice President Cheney while he was giving a televised speech Monday morning.

The X appeared for only one-eighth of a second, the network said, but the stark, if fleeting, image provided plenty of fodder for conservatives weighing in on the Internet yesterday. The tempest arose when Matt Drudge trumpeted the image on his popular news roundup, the Drudge Report, on Monday evening.

While right-wing bloggers hinted that the X could have been a deliberate subliminal message, a CNN spokeswoman, Christa Robinson, called it a “very, very insignificant” technical malfunction.

“Upon seeing this unfortunate but very brief graphic, CNN management immediately investigated,” the network said in a statement. “We obviously regret that it happened, and are working on the equipment to ensure it is not repeated.”

The statement also emphasized that the incident was a “technical malfunction” and was not linked to a human error, where political bias could come into play.

The network also addressed the issue on the air yesterday. In a segment that lasted about a minute, a CNN anchor and a technician took viewers inside the network’s control room to show what happened.

They said the X graphic was called a “switcher” and was used in the control room to cue tape for air.

The CNN officials could not explain exactly how the glitch occurred, and compared it to when a computer inexplicably freezes, forcing the user to reboot.

The incident occurred shortly after 11 a.m. Monday, during a live broadcast of a speech by Mr. Cheney. In a talk at the American Enterprise Institute, the vice president was promoting the Bush administration’s policy in Iraq.

He defended the decision to stay the course against insurgent attacks. “It is a dangerous illusion to suppose another retreat by the civilized world would satisfy the appetite of the terrorists and get them to leave us alone,” Mr. Cheney said.