How is this home drive shared?
OS X can use file extensions or meta-data about the file in order to determine the file type and how to open it. If stored to a native OS X HFS+ filesystem, then the meta-data is stored within the filesystem itself. On network shares that are AFP volumes, the meta-data is sent along with the file information and the host environment figures out how to store it -- most importantly is that OS X basically sees the file and meta-data just like a native volume.
If you use a non-OS X protocol like SMB/CIFS or NFS, OS X will write the file data and the meta-data separately. The meta-data is stored in a file with the prefix '._'. So, say you have a file named 'My Document', there would be in the same directory a file called '._My Document' created that has all the meta-data. When a Mac accesses a non-native filesystem, the operating system knows to use the dot-underscore files and it does the correct thing when copying files back and forth (merging the meta-data back into the native filesystem, for example).
In your scenario, it sounds as if the meta-data is being lost. This could happen if the meta-data files were deleted for some reason, or the file server prohibited access to files starting with '.', or any of a slew of other reasons. You might consider using the Terminal to check if the meta-data files exist and are accessible.