Cognitive Dissonance

"Cognitive dissonance is an uncomfortable feeling caused by holding two contradictory ideas simultaneously. The "ideas" or "cognitions" in question may include attitudes and beliefs, the awareness of one's behavior, and facts.

The theory of cognitive dissonance proposes that people have a motivational drive to reduce dissonance by changing their attitudes, beliefs, and behaviors, or by justifying or rationalizing their attitudes, beliefs, and behaviors."

From Wikipedia.

The discomfort of cognitive dissonance also makes people really cranky on forums when they're confronted with ISO 800 files that suck.