Work-content dissatisfaction

This organization recruit enginners keeping in mind certain type of projects, especially more techno-oriented.

Some time to begin with & sometime after completion of the project at hand employee is made to work on mundane project. Disillusioned employees start looking for another job.

Whereas company eventhough strategically look for certain projects by sheer business compulsiona have to acept the less desired projects also.

What would you suggest to solve this dilema