(FORTUNE Magazine) – Here are a few things that Mark Goldston would like you to know: that long before he found himself running an Internet company, he was an inventor in his spare time. That, as president of L.A. Gear, it was Goldston who invented the sneaker company's fabulously successful (albeit briefly so) lighted running shoes. That before that, as chief marketing honcho at Reebok, he invented Reebok's inflatable "pump" sneaker. That while other people have taken credit for the achievement, two patents for that pump sneaker hang on his office wall, and it's his name that is on them.

Got that? There's more. Goldston, 45, also wants you to know that Netzero, the Internet service provider that he currently runs, has a 30-terabyte Oracle data warehouse, the second-biggest Oracle warehouse on the entire Web. Maybe you don't know what a 30-terabyte data warehouse is. That's okay. Goldston wants you to know that, though he has marketed sneakers, perfume, and bagels in his career, he is just as comfortable talking about data warehouses and cluster dumps as any career technologist.

This is a man who feels he has a lot to prove. Perhaps it's because the last two companies that Goldston ran, L.A. Gear and the Einstein Noah Bagel chain, were high-profile disappointments--fiascos that Goldston wants you to know were not his fault. Spend a couple of hours with him and you will find yourself subjected to an extraordinary mix of trenchant analysis, braggadocio (Goldston never bothers to mention that his name isn't the only one on those sneaker patents), and self-justification.

If all goes well, Netzero will be the instrument of his comeback. But can Goldston find salvation via a company that loses money every time somebody uses its service, a company, moreover, that already faces stiff competition from much bigger competitors?

In the mid-1980s and early 1990s, Goldston was a rising star. At the age of 31 (this was before the advent of 22-year-old CEOs) he was made president of Faberge's U.S. division, where he turned around the struggling fragrance maker. Out of a job after Faberge was sold, he went on to head up marketing at Reebok during a period in which it made the hottest sneakers on the market. From there Goldston went on to L.A. Gear, a dying shoe company that the marketing superstar was supposed to fix.

But despite Goldston's short-lived hit with the lighted sneakers, L.A. Gear never recovered (it has since gone bankrupt), and Goldston was out after three years, an experience that still leaves him feeling bitter. He says he quit when L.A. Gear Chairman Stanley Gold insisted on getting out of men's shoes--a strategy that Goldston says was doomed; he even keeps a flattering magazine article from those days that outlines the strategy that he would have followed. After L.A. Gear, he went on to head Einstein Noah Bagel, a spinoff of the famously mismanaged Boston Chicken. This time, Goldston left after 21 months, as Boston Chicken's debt-laden franchisees started going out of business and the parent company's precarious finances began to unravel. Many, if not most, of the problems at both companies weren't his fault. But by the beginning of 1998, Goldston was a consultant with two notorious bombs on his resume.

When Goldston took the top job at Netzero--the first big U.S. company offering free Net access to anyone willing to live with a stream of targeted ads--in March 1999, most analysts called it a dot-com mission impossible. Netzero depended on advertising. But ads didn't cover its network costs. For every hour that a user was logged on, Netzero lost money. And that's not even counting marketing costs. Talk about a crummy business model.

Or is it? Netzero still loses money for every hour a user is logged on, but the gap between ad revenues and access costs has shrunk. When Goldston started, the price Netzero paid for access was 45 cents an hour. Thanks to bulk deals for bandwidth and an across-the-board drop in the price of access, that cost is now down to about 27 cents an hour. Goldston says that when the costs fall to 24 cents an hour--a point clearly within sight--Netzero's ad revenues will cover its access costs. Meanwhile, Netzero is rolling out fancier ad services, including television-like 30-second commercials that can be beamed to Netzero subscribers when they log on.

All this sounds like good news for Goldston and his reputation, but there's another twist: Like many innovators, Netzero is a victim of its own success. Having seen from Netzero's example that the underlying economics of free access might someday work, all the big Net players have jumped in. Excite@Home is offering free access. Kmart has teamed up with Yahoo to promote Bluelight.com, its own free-access subsidiary, quickly gaining a million users. And a San Francisco company called 1stUp offers a branded free-access service to any company that wants to use its network.

Goldston dismisses the competition. "If people think it's hard to make money with our model," he says, "how can 1stUp do it when it absorbs all the costs and splits the revenues in half?" (1stUp CEO Charles Katz says that the company does split revenues with partners, but would not confirm the exact split.) It's a good point, but if anybody can see the difficulties of his position, it should be Goldston himself.

In his own book, The Turnaround Prescription, Goldston tells the story of a small consumer-products company called Minnetonka, which he says invented liquid soap. The product was a huge hit. And Minnetonka? It got crushed as giants like Procter & Gamble seized on its innovation.

Naturally, Goldston denies he has a Minnetonka problem. With three million registered users (half of whom are active in any 30-day period), Netzero is still the biggest free ISP. He thinks Netzero will thrive thanks to the combination of first-mover advantage and its big budget for marketing, not to mention that 30-terabyte warehouse filled with reams of data about user demographics and surfing patterns, which Netzero can use to target advertising.

It's plausible, but don't count on Netzero remaining independent. Even if free Net service works, behemoths like Yahoo and America Online, should they choose to get into the game, may crush Netzero. But, as Goldston's own book recounts, Minnetonka did manage to sell its flagship Soft Soap line to Colgate-Palmolive for a tidy profit. Even that kind of equivocal success might help restore Goldston's track record and get him back some of the esteem that he so clearly craves.