ArcCatalog fails to start when the user clicks on the ArcCatalog icon on the ArcMap standard toolbar.
A raster layer in ArcMap's table of contents is stored in ArcCatalog's default drive location.
Optionally, download and install the Service Pack 1. Click on the link in Related Information, below. Click on ArcGIS-ArcEditor and under Version 8.1, select ArcGIS Service Pack 1.