Users unable to compile Book in Indesign with files on the network

Hi,

I have 3 computers that is having difficulties with being unable to compile a book in InDesign CS5.5 with files on the Network.

This has only recently started to happen.  I have another 3 computers that do not have the same issue.

All machines are Windows 7, and all have similar hardware specs.

The error appearing is....

Any help would be appreciated.

Checked server and all users have correct access to server and folders