"Computer Trouble" joke

Judy, the editor of a trivia publication, was having trouble with her computer. So she called Dave, the computer guy, over to her desk. Dave clicked a couple buttons and solved the problem. As he was walking away, Judy called after him, "So, what was wrong?"

And he replied, "It was an ID ten T error."

A puzzled expression ran over Judy's face. "An ID ten T error? What's that.. in case I need to fix it again??"

He gave her a grin, "Haven't you heard of an ID ten T error before."

"No," replied Judy.

"Write it down," he said, "and I think you'll figure it out."

She wrote: ID10T