Microsoft Project 2007 Corrupting Data

I have a split situation. At work I use MS-Project 2007 and at home 2003.
To ensure transportability filers are always saved in 2003 MPP formats.

However when I save files from 2007 they appear scrambled if I try and load them on either 2003 or 2007 about one time in ten.

The rows which had previously been displayed sequentually are all over the place. The bulk of the mix up are normally towards the bottom of the project plan.

A typical error message reads:

Microsoft Office Project

No calcualtions can be performed now.

There is a circular relationship on task XXX [Task Name]. The successors of this task refer back to this task or its predecessors causing a circular reference.

To remove the link that is causing the circular reference, select the two tasks that are causing the circular link, and then unclick Unlink Tasks on the Standard toolbar.

Surprise, surprise the item refered to had no circular link. Is anyone else having this problem or know of the fix?

The Project was not saved in filtered form.