By Slash Lane

Published: 05:25 PM EST

Apple Computer tops the news when it comes to analyzing recent operating system usage market share numbers, but one market research firm says its data indicates overall Mac OS usage has suddenly hit a slight decline.

"Mac Intel OS usage is growing quickly, and currently has 0.62 percent usage market share, but overall Mac OS usage is slightly down," Net Applications wrote in a recent newsletter. "Back in December 2005 total Mac OS usage market share was 4.35 percent, but August 2006 numbers show total Mac OS market share down to 4.33 percent."

Net Applications speculates that while the slight dip may not seem to be a cause for concern to most observers, "the fact that Mac usage was steadily growing until this year's stagnation may be indicative of larger Apple problems."

Still, it's unclear how reliable the firm's market share figures are or how it tracks operating system usage.

In the same newsletter, the firm erroneously reported that Apple's iPod unit shipments hit an all time high at 12 million units in one quarter before stumbling.

"iPod sales peaked at over 12 million units for the 4th quarter of 2005, but have stumbled to 8.5 million and 8.1 million units the most recent two quarters," the firm wrote.

iPod sales actually peaked during Apple's first fiscal quarter of 2006, in which it sold over 14 million of the players.