The European Commission has launched a second investigation into uncompetitive practices by Microsoft.
The commission confirmed that it has sent out letters to computer manufacturers and original equipment manufacturers (OEMs) investigating the terms of their licensing deals with the Redmond giant.
But it stressed that at this stage it is fact finding rather than making specific allegations.
"Other then the public statements by the EU we've had no contact with them," said Microsoft spokeswoman Tiffany Steckler.
"From what we've read they are seeking information from others and this is a routine step. Microsoft is already working under very strict regulations and scrutiny in our businesses with PC manufacturers."
Details of the recipients have not been released, but IBM, Hitachi and Toshiba are thought to have been contacted.
In the Department of Justice hearings in the US, Sony alleged that "Microsoft will use its monopoly power to force its OEM licensees to give up intellectual property rights, thus affording Microsoft the opportunity to expand its power".
Meanwhile, Microsoft is rumoured to have been in talks with Google about a possible partnership or takeover of the search engine giant.
Google is reported to have rejected Microsoft's approach, but neither company would comment on the speculation.
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