2. They don't handle uncertainty well.

During an economic downturn, rumors about layoffs, mergers, acquisitions and plant closings spread through businesses like oil spills--fast, thick and toxic. They create uncertainty and depress morale. And if there's one thing Generation Y can't tolerate, says Haefner, it's uncertainty--because they're not used to it, having grown up with immediate gratification and instant access to information. "Ambiguity drives them crazy," she says. "They want an answer."

3. Last one hired is sometimes the first one fired.

In organizations where seniority counts, Generation Y professionals may be at a disadvantage. Consultant Crane says millenials are concerned that they'll be the first ones affected by a layoff because they're among the youngest employees.

4. They have little or no prior work experience.