I seem to be having a problem with extracting one particular .zip file, the archive for the Lidar DEM data for tile 513_3937. I have been extracting and processing many of the tiles and this is the first one i have had a problem with.

I get tiled Lidar DEM data from http://opentopo.sdsc.edu/gridsphere/gridsphere?cid=standarddems

I maneuver to the tile in the on-line map and right-click. The archive (.zip) file downloads ok. I have downloaded it twice, once a couple months ago and once recently. the specific download URL is:
http://cordillera.la.asu.edu:8080/SoCAL/SocalMapServlet?mapid=513_3937_Garlock_Corr9_PolyB.zip

When I go to extract the .zip i get the following error message from the 7-Zip software that "513_3937.zip is not a supported archive"

IZArc reports that 513_3937.zip has a bad zip header but will still extract it. I have reviewed the resulting datasets in ArcCatalog. The fg versions of the datasets look normal. On the ug side the hillshade is missing and the ug DEM looks like it had processing problems. We are using the fg versions.