MSN Ad Exec Joanne Bradford Leaves Microsoft

Microsoft has been hit with the loss of another key executive.

Joanne Bradford, who was chief media officer for the company's MSN Media Network, has resigned to join advertising startup Spot Runner. Bradford had also previously served as Microsoft's VP for sales and marketing and as chief media revenue officer.

Her departure comes at a time when Microsoft is struggling to make inroads in the online advertising market against entrenched rivals like Google, AOL, and acquisition target Yahoo.

Spot Runner specializes in providing affordable television advertising services to small businesses. Founders Nick Grouf and David Waxman previously worked together in 1995 to launch Firefly Network, which was eventually sold to Microsoft and became the foundation of its Passport and .Net services.

Bradford's resignation marks the fourth departure of a top Microsoft executive this year.

The company in January confirmed that Rob Short, corporate VP for Windows Core Technology, had quit. Short, a 19-year Microsoft veteran, led the team responsible for designing, developing, and testing core components of the Windows operating system -- the latest version of which is Vista.

Earlier this year, Microsoft Business Division president Jeff Raikes said he would retire in September, to be replaced by former Juniper Networks chief operating officer Stephen Elop.

Microsoft's mergers and acquisitions chief Bruce Jaffe stepped down at the end of February.

To boot, Microsoft chairman Bill Gates will give up full time duties at the company in July.

The departures highlight one of Microsoft's biggest challenges as a mature company -- attracting and retaining talent. In its early days, Microsoft could entice recruits with an entrepreneurial environment and stock options that turned secretaries into millionaires.

In 2008, however, it's hot Web 2.0 startups that are offering those kinds of perks and incentives. In a statement, Bradford said she left Microsoft to join a company she called "visionary and entrepreneurial."