398 - ID ten 't' error

I found a tidbit for Saturday after all.

Techie John
I was having trouble with my computer.
So I called John the computer guy, to come over.
John clicked a couple of buttons and solved the problem.
He gave me a bill for a minimum service call.
As he was walking away, I said, "So, what was wrong?"
He replied, "It was an ID ten T error."
I didn't want to appear stupid, but nonetheless inquired, "An, ID ten T error? What's that ... in case I need to fix it again?"
John grinned .... "Haven't you ever heard of an ID ten T error before?"
"No," I replied.
"Write it down," he said, "and I think you'll figure it out."
So I wrote down: - I D 1 0 T
I used to like John ............
.