ArcMap crashes when displaying labels

Description

Displaying labels for a feature class crashes ArcMap.

Cause

The feature class being labeled contains non-simple or invalid geometry.

Solution or Workaround

1. Use the Repair Geometry tool located in ArcToolbox > Data Management Tools > Features > Repair Geometry to loop through all features and verify that the geometry is valid or simple.
2. If the data is in shapefile format, recreate the spatial index in ArcCatalog. For more information, refer to the following Knowledge Base Article: How to: Build a spatial index for a shapefile.
   
   If the data is a geodatabase feature class, this step is not necessary. Geodatabase feature classes have spatial indexes by default.