When Apple released Mac OS X 10.5, frequently referred to by its code name "Leopard," the company immediately had to deal with scattered technical problems.

Among the widest reported was the "Blue Screen of Death," where the Mac froze during the installation process on the blue startup screen. The issues led one consultant to blog "it's a dark day in Apple land when the least positive attributes of Windows start showing up in their beloved BSD-based OS."

What a difference a year makes. Apple has weathered the problems, morphed both its iMac and MacBook systems to aluminum cases with clean lines, and plans to release the sixth revision, code named "Snow Leopard," to its flagship operating system.

Next year, the company could hit a milestone that it's missed for a long time and claim at least a 10 percent share of U.S. computer shipments. The company has regularly grown its shipments in the United States, reaching a 9.1-percent share in the most recent quarter, according to data from IDC.

"We have seen Apple to get back into (nearly) double-digit market share which we have not seen for a long time," says Michael Gartenberg, VP of mobile strategies for JupiterMedia. "Even in a hard economy like we have now, that will put Apple in good stead."

Along the way, Apple—and its competitors—have learned some important lessons this year, analysts say.

1. Fix problems fast

When Leopard first hit the shelves, people reported major technical problems, including the Blue Screen of Death. Yet, most people today don't remember Leopard's rough start.

"Overall, Leopard is a pretty stable operating system at this point, but the interesting thing is that it really wasn't so when it shipped," says Michael Silver, VP of research for Gartner.

Apple's ability to quickly identify the problems and release fixes successfully turned what could have been a major black mark for Apple into a minor blemish. Microsoft has had less success dodging a problematic reputation for its flagship operating system, Windows Vista. It's not necessarily an apples-to-Apple comparison: Windows Vista is a major rewrite of Microsoft's operating system, while Apple's Leopard is a minor revision. Still, Microsoft's failure to quickly fix the problems left the company with public relations damage, Silver says.

"Certainly it was a rocky road to start with Leopard, but Apple was able to make changes much quicker, and it was able to avoid that reputation that Vista has been stuck with," Silver says.