Crash when using "Change Layout" to go to a map template containing an inset map

Hi.

I have a series of map templates that have an inset (locator) map on them as an additional data frame.

When I start a new ArcMap session and select any of the templates they work fine, however if I am already in a session and use the Change Layout button to go any of the templates then ArcMap locks ups and I have to kill it with Windows Task Manager.

If I remove the inset map on the templates, then I have no problems in using the Change Layout button, so it is this combination that seems to be the problem.

Does anyone have any suggestions?

I have tried storing the templates locally instead of a network drive, but it makes no difference.

I am running ArcGIS Basic 10.1 SP1 on a Windows 7 PC.

Kind regards
David Robertson