Problems Reading MSDOS disks on an Amiga A1200

I was having difficulty reading DOS disks on an Amiga A1200. I could get it to mount the disk but not read it. After much head scratching I discovered the following file was missing in the L directory:-

CrossDOSFileSystem

It seems that version 3.1 of AmigaOS doesn't have this file. However, all is not lost as version 3.0 does. Transferring from the Workbench disk of version 3.0 (show All files first) to my HD cured the problem. I have no idea if this is just my (genuine) copy of 3.1 has this problem. Moral of the story is hold on to your version 3.0 disks, they may come in handy...