You may get this error when you try to Send to Maya.
The problem is that Softimage is trying to write a file in the folder Data/XSI_SAMPLES/Simulation, where it doesn’t have write permissions.
The solution is to set a new active directory (so that you no longer see XSI_SAMPLES listed in the XSI title bar). You’ll have to restart Softimage, because Softimage appears to cache the current project location at start up.
When you do a Send to Maya, the OneClick plugin writes an FBX file to the Simulation folder.