A malfunction in the Harvard Coop's computerized billing program resulted in an erroneous finance charge on many December bills, Coop president Jeremiah P. Murphy Jr. '73 said yesterday.

Some Coop customers did not receive billing statements for November but were billed for late charges in their December statements, he said.

The error resulted from a glitch in the software the Coop uses for billing, he said.

"We didn't notice until we had a couple of customers call up and ask about it," he said.

"I think there's some concern with some customers. No one likes it, but there's an understanding," he said.

The problem escaped the notice of Coop employees because billing for the Coop is processed by a computer program run by another company, Murphy said.

Because of the separation between the Coop and the billing processors, there is sometimes a "possibility" that a faulty finance charge could be assessed without the customer's knowledge, he said.

"In a lot of cases, you occasionally have computer glitches that throw things off," he said. "There can be occasional glitches on individual accounts as well."

He said that most glitches on individual billing statements are usually noticed and reported by customers.

Murphy did not disclose how many customers were erroneously charged, or how much in additional finance charges was levied.

The Coop's credit office refused to comment on the situation yesterday.

Controller Tom Wagner and General Manager John Donaldson could not be reached for comment.

The Coop is working with the company handling the billing to reprogram the software and to correct the inaccurate finance charges, Murphy said.

Murphy said he does not foresee such problems in the future since the traditional Coop charge cards are no longer issued