As a 90-year-old grandmother, Pauline McKee tries to maintain a sweet disposition.

When she played a penny slot machine that told her she had won more than $41 million, the Antioch woman remained pretty calm. "That was nice," she said, recalling her reaction. "Very nice."

And when she learned on Friday that the Iowa Supreme Court ruled the casino does not have to pay her the big bucks, McKee took it stoically.

Instead, she won a mere $1.85 on the bet.

"I had my doubts from the start, because that's a lot of money for a penny machine," she said. "I was hoping to help my children out financially, but it wasn't meant to be."

The court ruled that the Isle Casino Hotel in Waterloo, Iowa, does not have to pay McKee the $41.8 million she thought she had won in 2011 while playing the "Miss Kitty" slot machine.

The machine gave her a 185-credit win and declared on the screen, "The reels have rolled your way! Bonus Award $41,797,550.16."

But the court sided with the casino and said the game's rules capped jackpots at $10,000 and didn't allow bonuses. The court said the message about the bonus award was a "gratuitous promise" the casino didn't have to honor.

McKee said she is a widow who lives on Social Security, can't see well and is a grandmother of 13. She had been at the casino during a family reunion.

McKee sued to try to collect the prize after a state investigation concluded the bonus award wasn't valid and resulted from a software error.

The ruling noted the casino paid McKee the $1.85 she was owed, and gave her a free hotel room that night.

McKee said she still plays the slots occasionally — but not at Isle Casino. "They didn't give me anything except what I had on the machine," McKee said. "If they're not going to give me any money at all, that's terrible."

The casino could have been forced into bankruptcy if it had gone the other way, said one of its attorneys, Stacey Cormican. A $41 million payout would amount to about half of the gross revenue the casino generated last year.

Cormican said the ruling will ensure fairness in Iowa's large gambling industry.

"Casinos are required to post rules and follow those rules. If either the patrons or casinos could change the rules in the middle of the game, it would be absolutely chaos," she said.

She said such computer glitches are rare.

According to the lawsuit McKee filed against the casino, here's what happened on the night of the disputed winnings:

McKee's daughter had invited her to sit down next to her to play the "Miss Kitty" slot machine.

At one point after playing 25 cents, the machine's video screen indicated her win was 185 credits, or $1.85. But it also displayed a notice of a "bonus award" of almost $41.8 million.

McKee and her daughter summoned an attendant, and an employee opened the slot machine's main door to clean the central processor. The supervisor photographed the display, and a slot technician restarted the game.

The supervisor said she had to make a few phone calls and gave McKee a $10 card to play other games while she waited. The supervisor paid McKee $18.10 she had won overall on the machine up to that point, said the casino was looking into the machine and told McKee she would get a free hotel room that night.

The next day, the casino's vice president and general manager called the situation "unusual" and compensated McKee's family for additional hotel rooms they used. McKee was told the casino had contacted the Iowa Racing and Gaming Commission and that the machine would be secured and studied.

The Gaming Commission conducted its own investigation through a testing laboratory, which concluded that the machine's hardware erroneously awarded the bonus, the suit said.

The manufacturer of the game, Aristocrat Technologies, had previously issued a bulletin that the game might show an erroneous bonus, with a recommendation to casinos to disable the bonus option.

The court ruling states that by playing, McKee entered a binding contract governed by rules and a pay table which could be displayed on the machine by pressing a button on the slot machine. A sign posted on the front of the machine also states, "Malfunction voids all pays and plays."

The rules made no mention of any bonus, so therefore the court, in an opinion written by Justice Edward Mansfield, concluded that McKee was entitled only to the $1.85. The decision upheld a lower court's granting of summary judgment to dismiss the case.

"Any message appearing on the screen indicating the patron would receive a $41 million bonus was a gratuitous promise and the casino's failure to pay it could not be challenged as a breach of contract," Mansfield wrote in a ruling that dismissed a lawsuit filed by McKee seeking the payout.

McKee's argument that the casino had an implied contract with customers to pay whatever the slot machines said "is contrary to precedent and general contract principles," he added.

The ruling followed similar decisions by other courts, such as a Mississippi Supreme Court ruling that a gambler was limited to the $8,000 maximum payout in the rules, rather than the $1 million bonus displayed on a game's screen.

In other cases, the courts have ruled in favor of gamblers if a bonus was provided for in the rules, or when a casino changed the rules after the game was played.