Miller, who will remain with Emachines until a replacement is found, will join Swell.com, a sports content and e-commerce company, as CFO.
Emachines, which went public in March at $9 per share, tumbled more than 12 percent this morning to $5.31. The stock has traded as high as $10 and as low as $4 since its debut.
Last year, Apple Computer filed a suit against Emachines and several distributors, complaining that the companies were selling an iMac knockoff. The suit was settled in March; the terms of the settlement were not disclosed.
In April, the company reported a surprise profit and said it is working on two lines of inexpensive Internet appliances to be released next year.