Nokia has announced its CTO, Richard Green, will be going on leave due to what the phone manufacturer refers to as a personal matter.
Henry Tirri, head of Nokia research centre, will take over from Richard Green in the interim. It is unknown when Green will return.
Nokia said: "Richard Green has taken leave to attend to a personal matter. We have not provided a specific timetable for this return."
"This has no impact on Nokia's product strategy or expected product launch timelines."
Nokia is expected to unveil a Windows Phone 7 device by the end of 2011.
Green's absence adds to a turbulent time for the phone maker.
Nokia warned that sales of its Microsoft Windows phones will substantially slump in the second quarter of 2011.
Gartner recently reported that Nokia's sales fell to a 14-year low.
In a 6-K document filing with the US Securities and Exchange Commission (SEC), Nokia cancelled its annual outlook and said it expects device and services sales to be substantially below anticipated sales of up to €6.6bn (£5.8bn) for the second quarter of 2011. The company expects its operating margin to break even for the quarter.
According to the Financial Times, US private equity firms and consortia have been bidding for a majority stake in Nokia.
However, at a conference in London, Stephen Elop, Nokia's CEO, said Nokia was not for sale: "All the rumours are baseless," Stephen Elop confirmed.
Nokia and Microsoft confirmed a strategic partnership in February, with Nokia adopting Windows Phone as its primary smartphone strategy and Bing as its search engine. Nokia will also fold its Ovi store into Microsoft's online Marketplace.