Bug in GDAL 1.7.0
A serious bug has been found in the recently released GDAL 1.7.0. HFA files created with the new version of GDAL are not compatible with Erdas ViewFinder, ArcGIS, ArcExplorer and other programs. Such files can only be opened with GDAL itself.
The interim bugfix release 1.7.1 is scheduled for Monday. It is not recommended to use version 1.7.0, it will be declared deprecated after the bugfix release.
A fix was committed just two hours ago: trunk (r18728), branch 1.7 (r18729).