Motorola stockholder and longtime critic Carl Icahn is seeking answers about the company's floundering performance, filing a lawsuit today seeking documents related to Moto's beleaguered mobile device division.

In a letter to shareholders, made public this morning before the stock markets opened, Icahn called for Motorola (NYSE: MOT) meeting minutes detailing how the company's board of directors selected its mobile unit's executives, and other documents specifying the company's strategy for its troubled handset business.

He also nominated a slate of four candidates for the company's board of directors.

Additionally, Icahn blasted the appointment of CEO Greg Brown, who replaced Ed Zander in January and announced steps to get the company's handset division back on solid footing.

"What 'qualified' Greg Brown to be the CEO?" Icahn said in his letter. "He certainly -- as far as I can ascertain -- has no in-depth experience or knowledge concerning the Mobile Devices business, which was and is by far the major problem for Motorola."

"What we got instead was a year of revolving-door executives, a leadership vacuum, and accelerating deterioration at Motorola's Mobile Devices unit," he wrote.

Moto's stock closed up 4.76 percent on the news, at $9.69. Icahn's letter noted that market value over the past 18 months has fallen by over $37 billion, by about $17 per share.

As of press time, a Motorola spokesperson said the company had not yet received a copy of the lawsuit, which Icahn filed in Delaware's chancery court.

Icahn's legal action comes as the company is trying to right itself after declining sales.

Since assuming personal oversight for the mobile device unit, Brown has replaced several executives, as well as key company financial, marketing and HR leaders. The latest personnel moves focused on accounting division heads.

In an e-mail last week to InternetNews.com Motorola stated it is "pleased with the valuable additions we have made to our senior leadership team, including talented new heads of our finance and human resources functions."

The executive shuffle, which included the resignation of mobile service honcho Stu Reed two weeks ago and European counterpart Mike Fenger just last week.

Industry pundits, for their part, have been split on whether the many executive changes, and Brown's heavy lifting in the mobile devices unit, indicate a new strategy or a potential sale scenario.

Motorola, which has initiated an executive search to fill Reed's slot, said Brown's focus has been on "executing Motorola's strategy to improve financial performance and delivering value for our shareholders."