This started with one computer not being able to "see" the homegroup though it was "seen". The reason seems to be an error 7024 that the HomeGroupListener terminates because there are not enough "endpoints". I tried a variety of things including not loading any non-MS service, turning off the firewall, turning off defender, virus scan, delaying the service start but there was no change. SFC /scannow did see a problem with OpenCL.DLL that it couldn't repair but from what I've read that seems an unlikely issue.

I tried to see what all the endpoints were using the MS tool dbgrpc and it gives and error 1734 which means "The array bounds are invalid". So this is all consistent - bad array bounds means no more endpoints means no HomeGroupListener but why the invalid array bound? Also, puzzlingly, shouldn't this cause a lot more errors?

Anyone any ideas?? Please!!