Hello, I use 3ds Max 2010 on my home computer but will often work on computers that have both 2009 and 2010. I recently tried opening a file on my home computer (2010) but it couldn't open the file (there's no more information beyond "Can't open file _____". I had this problem back when trying to load 2009 files in 2008…
max files are not backward compatible they are forward compatible tho. Files saved in 2010 wont open in 2009. it works the other way round tho. If the file wont open try using the merge command. otherwise the file is corrupt
for transferring most data the fbx format is quite useful .. but jey it would be fantastic if you could open newer max files in older max version (like photoshop supports)