It's 10:00 a.m. on a warm summer day in Princeton, N.J., and as a visitor approaches the split-level house behind a lawn sprinkled with toys, the yellow Labrador retriever makes a half-hearted attempt to rise. He barks twice, then goes back to snoozing in the sun. There isn't another sound on the leafy street. In short, it is another workday in the suburbs.

Except inside the house.

It takes a little while for a more than slightly distracted Lisa Smith Nielsen, 33, to answer the door bell. Holding in her right hand the device shipping clerks use to seal boxes with packing tape, she blurts out an "Oh, hi," through a pen clenched in her teeth.

"You have to excuse me," she says. "The UPS man is coming and I haven't finished packing the boxes." She looks at the cartons stacked -- precariously -- on the piano and sighs. "It'll take about 15 minutes."

For nearly the next hour, she alternates between stuffing boxes and typing out shipping labels on the battered manual typewriter atop her dining room table.

Or she tries to, anyway. But the door bell keeps ringing.

First it's a woman from down the block who's locked her keys in one car and needs to borrow a car seat for the other, which Nielsen lends. No sooner does she sit back down at the typewriter than the bell rings again. It's the man spraying her neighbor's trees, suggesting she move the dog out of the line of fire, which Nielsen does. And so it goes.

But despite the interruptions, she has the boxes packed and ready a good six or seven minutes before the UPS truck pulls into her driveway.

It is only then that Nielsen -- mother of two, stepmother of one -- can sit down in her living room and talk about her product, which, according to the can, "helps combat wicked witches, big bad wolves, mean ol' pigs, spooky ghosts, nasty gremlins and hordes of other things that go bump in the night!!!"

Every year in the United States hundreds of thousands of new businesses start up -- and Lisa Smith Nielsen, much to her own surprise, is running one of them. For the transition from being a book editor for William Morrow & Co. to becoming president of the company that produces Scare Spray, Nielsen has her daughter, the now four-year-old Sarah, to thank.

W. C. Fields once said, "Anyone who hates children and dogs can't be all bad." But then, old W.C. never met Sarah. She is bright, funny, and has a vivid imagination. So vivid, in fact, that about two years ago, Lisa and John Nielsen were just about ready to give her away. Cute, lovable Sarah was waking up in the middle of the night -- every night -- screaming. A giant pig was crashing through her wall.

"We had no idea where the idea came from," Lisa Nielsen says. "We never read her The Three Little Pigs or told her stories about pigs, and no matter how we tried to reassure her, it didn't matter. Every night the same pig -- Sarah was never really able to describe it -- came into her room. We tried reasoning with her, explaining that there was no pig. We tried to joke her out of it. We even tried to humor her -- we would run around the room saying, 'Shoo, pig.' But nothing worked. She'd get through the night, but the next night, the pig would be back."

The Nielsens -- growing more tired by the day -- began desperately searching for advice. Their pediatrician was no help. "She'll outgrow it," he said. Friends commiserated but could offer no specific suggestions, and specific suggestions were what they needed. Sarah continued to wake up screaming.

When all else fails, ask Grandma and Grandpa. Nielsen's parents sent her a newspaper clipping that described how another mother had made imaginary creatures vanish by spraying her child's room with hair spray. Nielsen was intrigued -- for a couple of reasons. Maybe the spray would work, and she could finally get some sleep. But also she began looking at Sarah's pig in a different way. If Nielsen was having this problem, and the woman in the newspaper story was having this problem, maybe others were, too. Maybe there was a business to be built. "My father was always self-employed -- he was a consultant for a while, and he ran his own greeting card company -- and so I always thought of things in terms of spotting an opportunity," she explains.

That entrepreneurial instinct, plus the sensibility of a 1980s parent, led her to start SBN (for Sarah Beth Nielsen) Products Inc. -- a real, if unusual, company. Consider its product.

While Nielsen loved the idea of using an aerosol can to make Sarah's pig disappear, she refused to use hair spray. "I worked so hard baby-proofing the house -- putting plugs in all the electrical outlets, gates by the stairs -- the last thing I was going to do was spray hair spray all over." A quick search of the shelves at the local supermarket didn't turn up any better choices. All the aerosol cans there contained things Nielsen didn't want in her house. It seemed that only air would be safe.

Maybe that's it! Can you buy cans filled with nothing but compressed air? Dozens of calls later, she was talking to a midwestern manufacturer who would be willing to sell her nothing -- for $1.50 a can, 100-can minimum, thank you.

The cans arrived right on schedule, and so did Sarah's pig. "We went into her room, explained that this was a magical can that would make the pig disappear forever, and we sprayed in every corner." The pig vanished and a business appeared in its place.

"We gave the can to friends whose children were having similar problems, and it worked. Then the question became, could we sell it?"

Nielsen stuck some labels on the cans of Scare Spray -- as she decided to call her balm -- and dragged them with her on a trip home to Texas. "I find Texas people more hospitable than the folks around here," she says. "And this was going to be the acid test, whether anyone would buy." She stopped at two children's boutiques and convinced them to take a few dozen of the cans, which retail for $5.95. Then she put her marketing plan into effect.

"I called my friends at the Dallas Morning News and told them the stores were carrying Scare Spray, and told them the story behind it. They did a small article." That made the boutiques happy; they sold out. It also gave her something to show when she called on a children's store in Austin. It bought, too, and Nielsen was in business.

She visited trade shows and cornered sales reps. "I explained to them I was just starting out, and I told them the story about Sarah -- and I guess they liked the fact that I was a helpless female," says Nielsen, who is anything but. For 15% of sales, some 40 reps are pushing Scare Spray across the country. Despite her unusual working conditions ("I sometimes park the car down the street, so nobody will know I'm home") SBN is on its way. She has sold more than 1,000 cans, giving her revenues of about $3,000.

Nielsen has reason to be optimistic. She switched to silk-screening her cans, to make them look more professional, and as a result has been forced to rent warehouse space to keep up with product demand.

Will that demand put her in Tom Peters's next book? After all, she is certainly keeping her costs down. Her office consists of space she carved out of her one-car garage, and she has been known to haunt trash bins outside of department stores to obtain some of her packing material.

But despite this resourcefulness, there are still major hurdles to overcome. For one thing, there is absolutely nothing proprietary about putting air in a can. While Nielsen copyrighted The Story of Scare Spray, the booklet that comes with each can, a competitor could still unveil an identical product.

Nielsen put the best face on the problem. "Competition would just expand the market, since it would increase awareness." But exactly how big is the market? She isn't sure. And isn't Scare Spray a onetime purchase? A can lasts for 40 short sprays -- enough, one might guess, to banish forever the scariest fiend.

But questions or no, Nielsen is optimistic. And despite working under conditions that Lee Iacocca couldn't dream of, she is experimenting with a second product -- one she would like to keep under wraps a bit longer.

Another business is underway.