Nortel Networks Ltd. (NYSE/Toronto: NT) COO Gary Daichendt has resigned after only three months on the job, the company said in a statement released this morning.

So what happened? In a short, blunt press release, Nortel CEO Bill Owens, who hired Daichendt, basically said the top executives couldn’t work together.

"It has become apparent to Gary and me… that we have divergent management styles and our business views differ,” said Owens in the statement.

Nortel also announced that Gary Kunis, chief technology officer, who joined Nortel following the appointment of Daichendt, will also be leaving the company. Kunis previously worked alongside Daichendt at Cisco Systems Inc. (Nasdaq: CSCO).

The departure of the two top executives throws Nortel’s leadership back into question, just days after Owens spoke at Supercomm, saying things were just dandy.

Owens told a packed auditorium earlier this week in Chicago that “Nortel is doing well -- business is good. We’ve been through a transition.” Clearly that transition hasn’t yet ended.

Daichendt, former executive vice president of worldwide operations at Cisco before retiring in 2000, looked to be in position to eventually take over the CEO spot (see Ex-Cisco Exec Named Nortel COO). Owens had shed some responsibilities when Daichendt came on board.

The departure of of Kunis means Nortel has gone through three CTOs in less than a year. In October 2004, Brian McFadden took over for Greg Mumford. In March, McFadden was replaced by Kunis, becoming chief research officer (see Nortel Changes CTO – Again ).

— R. Scott Raynovich, US Editor, Light Reading
(Ray Le Maistre, International News Editor, contributed to this story)