this means that you saved the document on the other machine with a newer version of InDesign. As INDD-files are not compatible with older versions you get the error message. But you have luck there is an easy solution. Go back to the computer with the newer InDesign and save the document as IDML-file. IDML (InDesign Markup Language) is an exchange and repair format and can be opened by older versions. I think down to CS3 oder CS4. If you used features that are not supported by an older version than you can still open the file.
btw: With repair format I mean, that if your document behaves not the way it should, than it could sometimes help to save the file as IDML to bring the bits and bytes back to order.
IDML can be opened by fully-patched versions of CS4 and later. If you need to open in CS3 you must first open in CS4, then export from there to .inx.
There are some caveats to using IDML to back-save for an earlier version. Any features used in the new version that don't exist in the old will be lost completely, and text will be recomposed using the text engine in the old version, so line endings may change and you may see overset text, particularly in long stories.
It's working! Thanks!