RealNetworks chairman and founder Rob Glaser has once again grabbed the reins as CEO, following the sudden resignation of Thomas Nielsen. Nielsen, formerly with Adobe and Microsoft, took over from previous interim CEO Mike Lunsford in November.

“I come back to RealNetworks with a sense of great urgency to set the company on a long-term path to success,” Glaser (pictured) said, adding that he was not a candidate to take over as CEO on a permanent basis. Glaser stepped down from that role in early 2010

RealNetworks was trading down more than 6 percent at midday. Check the current price here [RNWK].

Nobody can take away RealNetworks’ place in tech history as a streaming media pioneer, but it’s been awhile since it led the market. In the quarter ending March 31, RealNetworks lost $17 million on sales of $67 million. For the same quarter last year, it lost $12 million on sales of $87.3 million.

“The board and Thomas mutually agreed that the CEO position wasn’t the right fit,” Glaser said. “We thank Thomas for the contributions he has made in moving RealNetworks forward and wish him well in his new endeavors.”

Related links:

RealNetworks – press release

RealNetworks –

PaidContent – Another RealNetworks CEO is out; founder Glaser steps in

Venture Beat – Second RealNetworks’ CEO resigns after less than a year

Seattle Times – RealNetworks CEO resigns, Glaser returns

Forbes – RealNetworks CEO Nielsen Out; Glaser Returns As Interim