But Vaughan & Bushnell did not pay it because its license agreement said it could use the software on "any computer that is a direct and single replacement" of the original one, according to the complaint.

Now Infor is arguing that the hardware upgrade represents a breach of Vaughan & Bushnell's agreement, due to the newer system's additional processing power. But Vaughan & Bushnell contends the original license agreement "places no limits on the processing power of replacement computers."

An e-mail to the manufacturer from an Infor licensing official, which was filed along with the complaint, states that the list price of upgrading from a System/38 to an AS/400 is $1,034,000. But the e-mail does not explicitly demand that Vaughan & Bushnell repay that amount.

An Infor spokesman could not immediately comment on the matter Friday. Infor has not yet filed a response to Vaughan & Bushnell's complaint, which asks that any future legal claims by Infor about the company's use of the software be barred.

Vaughan & Bushnell was "quite surprised" at Infor's sudden demand, according to Richard Assmus, an attorney for the manufacturer.