Losing Data Validation Settings

Further to my question about data validation yesterday, I hope someone can help me with another DV problem.

I use several different machines in the course of my work, and I have been finding that the data validation settings are not retained when I open the file on another machine. I initally thought it was to do with the version of Excel I was using (I run 2011 for Mac and other users are on 2008 for Mac) but it happens even when I open it on machines running 2011.

The usual way this manifests itself is either the settings are just not set anymore, or the cells they refer to are changed (and wrong) when it's opened up on another machine.

Has anyone else encountered this? I'm trying to create an expenses form to be saved in a central location so it can be used by several members of staff.


TIA

ETA: I am using named ranges to create drop-down lists to select from and DV settings to prevent anything else being entered other than the list values.