Managing performance issues at work can be challenging, and many managers say it can be an emotional or painful process. It gets more difficult when an employee states the performance deficiencies are due to a disability. Frustration on the part of the supervisor often ensues. Sometimes when an employee makes this claim, a supervisor immediately sees the missing link with what has been occurring with the employee at work. But other times, the claim may sound like an excuse to shield the employee from being held accountable.