I am using 10.1 and in ArcCatalog I tried to export a file geodatabase with a raster dataset in it to a thumbdrive, and then open that raster dataset on a laptop with version 10. All the copying/exporting works fine, but when I try to add the raster to an MXD, I get the error "Invalid raster set. Failed to create raster layer". I tried creating a version 10 geodatabase in 10.1 and redo the same process of exporting, but it gives the same error. Not sure if it is something local to my computer, or an issue of downgrading files from 10.1. I installed 10.1 on the laptop and of course it opens the files with no problems.