Bill Morrow ClearwireThere’s trouble brewing over at Clearwire, the 4G network company in which Sprint holds a non-controlling majority stake. Chief executive Bill Morrow has resigned from his positions as CEO and executive board director, citing the usual “personal reasons,” the company announced today.

Current Clearwire chairman of the board John Stanton will replace Morrow as interim CEO. Stanton was formerly the head of VoiceStream Wireless, a company that in 2001 was bought out by Deutsche Telekom and was soon after renamed to T-Mobile.

Stanton’s rise in the company seems curious given that only a few days ago we reported that Sprint may be in talks to buy T-Mobile. The news also follows Clearwire’s abandonment of its retail strategy last month. Now the company is dedicated to being a wholesale network provider.

Clearwire was the first company in the U.S. to begin building a WiMax 4G network. It merged with Sprint’s WiMax 4G operation in 2008, and its investors include Sprint and Comcast. Sprint relies on Clearwire for its 4G network, and Comcast also sells wireless service on the network.

The company’s early bet on WiMax 4G technology may be part of the reason it’s having so much trouble now. AT&T and Verizon both decided to adopt the competing LTE 4G technology instead, and Sprint is also reportedly considering a shift to LTE in the future. Clearwire is planning an LTE network as well, but the cash-strapped company likely won’t be able to keep up with its bigger competitors.