Yesterday, Microsoft (NASDAQ:MSFT) posted a $6.2 billion charge against its fiscal fourth quarter revenues, writing off its 2007 purchased of online advertising firm aQuantive, and leading to its first quarterly loss since it became a publicly-traded company in 1986.

The acquisition of aQauntive was intended to give Redmond a beach head in the online ad market, countering Google‘s (NASDAQ:GOOG) dominance. Instead, Microsoft’s online ad division has floundered

, racking up about $9 billion in losses, while contributing  just 4% to annual revenues.

Microsoft reported a $492 million loss during the quarter, compared to a $5.9 billion profit during the same period in 2011.

Excluding the charges, earnings came in at 73 cents a share, solidly beating analysts who had predicted 62 cents a share, the Associated Press noted.

For the quarter, the company saw revenue of $18.06 billion, up 4% from last year, but falling short of the $18.15 billion analysts had forecast.

Shares of Microsoft fell more than 1% in Friday morning trading.

Sales of its Windows operating system slowed along with sales of personal computers, which have been trending lower due to the economic slowdown and competition from tablet computers like Apple‘s (NASDAQ:AAPL) iPad. Computer server and business software sales were up during the quarter.

The company is now looking forward to the October release of its Windows 8 operating system. Last month, the company unveiled its own tablet computer, running the new operating system, designed to compete with the iPad.