Robert Halderman: Motivated By Letterman Grudge?

Earlier this week, it was alleged that Stephanie Birkitt carried on her affair with David Letterman even as she lived with boyfriend Robert Halderman.

Halderman was arrested last week for attempting to bilk Letterman out of $2 million in exchange for keeping quiet about his interoffice romance(s).

Well, it looks like another factor on top of Birkitt's cheating may have motivated the CBS News producer - Letterman just plain didn't like the guy.

After Letterman broke up Stephanie Birkitt, a former Late Show staff member, and she began dating Halderman, Dave was not a fan, sources say.

Insiders say that Dave made it clear he didn't want her new 51-year-old producer boyfriend at any Late Show office parties and other staff events.

He wanted Stephanie there, just not her new squeeze.

Halderman liked to live well, golf and party. Office affairs aside (Dave was also tied to Holly Hester), Letterman is private, reserved and geeky.

Even the cultures of their workplaces were poles apart.

The Late Show boss, who in March married longtime girlfriend Regina Lasko, might have been playing around, but the female staffers all loved working there.

"I would be shocked if someone came forward with a sexual-harassment complaint," a female insider said. "I've worked in a lot of places, and [The Late Show] is one of the better places for a woman. Dave's not a groper."

Birkitt has since been banned from the set of the Late Show.