Symptom

Occasionally, while using the Business Client, there will be a .NET exception: Invisible or disabled control cannot be activated.

(.Net exception)

This is related to a situation within the .NET3.0 runtime, which cannot be resolved. The coding of the Business Client has been enhanced to reduce the number of occurrences to a minimum, but they will never be completely eliminated.

Solution

The only possible way to resolve this situation is to install the latest .NET runtime, at least install .NET3.5. See also 3 Installation and Client Configuration and 3.1 Desktop Installation.