My main work uses network drives for both workspaces and data. For convinience most of these are mapped by drive letters.
But if a workspace is attempted to be run with different credentials than my normal login, these may fail. The only work-around is to always manually enter the UNC paths instead of the drive letters.
My suggestion is to add an option to Workbench to have it automatically replace all non-local drive references to their UNC eqivalents when saving the workspace.
Cheers.