New York City workers spent much of Thursday and Friday removing the decals from the city's footpaths and walls.
"We intend to hold your firm directly responsible for this illegal, irresponsible and dangerous defacing of public property," said a City official in a letter to Microsoft.
After an initial claim that it had permission from the city to place the advertising material, Microsoft said it is now looking into the matter.
“We made a mistake with the decals, and we take full responsibility for what happened," said Microsoft vice president Yusuf Mehdi in a statement. “We're working with city officials to clean up the decals immediately.”
After a similar advertising campaign in April, IBM was forced to pay the city of San Francisco US$120,000 in fines and clean up costs. IBM was also fined by city administrators in Chicago for a “corporate graffiti” campaign.
In Australia in November 2001, Microsoft and its publicity agency run into trouble with several central Sydney councils after it spray painted promotional material for the then-new Xbox over city footpaths.
The New York Microsoft ads appeared in conjunction with the launch of the company's MSN 8 internet portal in the city's Central Park. Microsoft chairman Bill Gates teamed with Disney's Michael Eisner at the launch to announce the companies were partnering to deliver exclusive Disney content to MSN 8 subscribers.