iProcurement - error when clicking on link to Requisition from another user

In iProcurement, in the Requisition Tab with My Group Requisitions displayed, I click on the Requisition number or description links and then get the following error message:

"You have encountered an unexpected error. Please contact the System Administrator for assistance."

This does not happen for my own Requisitions.
The Requisition Document Security is set to 'Public'.

Any ideas how to resolve this?

Thanks
Gary