SigmaTel ( SGTL) said equipment issues at test and assembly facilities will contribute to third-quarter results coming in below prior expectations.The multimedia chipmaker said it expects revenue for the quarter of $74.4 million -- below the current Thomson First Call consensus of $78.6 million -- as well as gross margins below its prediction of about 51%. In addition, the revenue and gross margin shortfall will cut about 10 cents a share from the low end of the company's previous guidance. In late July, the company said it expected to earn 30 cents to 37 cents a share before items. Analysts had expected the company to earn 30 cents a share in the quarter. SigmaTel said the equipment issues were compounded by heavily back-end loaded demand during the latter half of September. Additionally, the mix of products sold during the quarter was hurt by this loss of production with a significant amount of higher-end products unable to ship, shifting the sales mix and driving down gross margins. There were a total of 1.3 million lost units that forced the rescheduling of the related orders to October 2005. Shares of SigmaTel, which supplies chips to Apple's ( AAPL) iPod shuffle player, were halted immediately ahead of the announcement. Following its return to trading, the stock fell $1.61, or 9.2%, to $15.60 on Instinet. SigmaTel shares have been in a tenuous position since it was discovered last month that its chips were not included in Apple's hot new flash-based iPod nano player. Instead, Apple chose audio processing chips made by PortalPlayer ( PLAY), which had previously only supplied audio processors for hard-disk-drive-based MP3 players.