Dear Jonathan J,
I have restored the camera to its default menu settings but to no avail. Eos Utility > control camera > still only permits 'Monitor Folder' ('Camera Settings/Remote Shooting' greyed out). The camera has not been damaged but has not been used for remote shooting for several years since I bought a 5D Mk 2. In other respects it functions normally though it has also stopped actuating specialized non-Canon flash on Manual settings. (I run a photomicrographic laboratory - Google <spike walker>!)
The camera is linked to my computer via a USB cable. There appears to be no problem with this arrangement since 'remote shooting' works perfectly when I replace the 1Ds Mk 2 with a 5D Mk ll.
I cannot rate it because you have not yet answered the question - just asked for more information about the technical background to it! Spike.