[dredmorbius]

Abuse of monopoly power as detailed in the Findings of Fact in the DoJ's case against Microsoft:

http://www.justice.gov/atr/cases/f3800/msjudgex.htm

In particular:

http://www.justice.gov/atr/cases/f3800/msjudgex.htm#v

There was more than just what the court found, however.