1.   And that is why the Justice Department wants to explore whether Microsoft is using its acknowledged dominance in the desktop software business to compete unfairly with other on-line businesses.

2.   Another theory involves a company using its dominance of one market to force its way into another.

3.   Antitrust officials fear that Microsoft is using its dominance in the operating system market to force out rivals in other software businesses.

4.   Both moves have been criticized by companies and customers who say Microsoft is using its dominance in operating software to move into other businesses.

5.   Both allege that Microsoft is illegally using its dominance of desktop computer operating systems to win control of the market for Internet browsers.

6.   But the commission said it did not yet have enough information to decide whether El Paso improperly used its dominance over the pipeline capacity to raise rates.

7.   During the trial, prosecutors argued that Microsoft used its dominance in the computer operating systems market to crush rivals and force its partners into exclusive contracts.

8.   Ever since, long-distance carriers have feared that the Bell companies would use their dominance of local telephone markets to compete unfairly in their market.

9.   In Italy, a government investigation found that Coke had unfairly used its dominance to muscle out competitors.

10.   Microsoft, they point out, has already used its dominance of personal-computer operating systems with Windows to establish leading positions in word processing and spread sheets.