Bug: Exporting a raster dataset does not support more than three bands
** This issue is addressed in ArcGIS 9.0 Service Pack 2 (SP2) **
When exporting a raster dataset with more than three bands, from the Export layer context menu of ArcMap, only three bands are created in the new raster dataset on disc.
Click on the link in Related Information below and download Service Pack 2, if necessary. **