Thanks for the link to SuperAntiSpyware - brilliant! It found oreans32 (which nothing else had found) and dealt with it, but that, in itself, made no difference.
The weird thing (to me, at least), is that everything is running almost exactly 2.5 times slower - from copying or transferring files to virus scanning, starting up and shutting down. I don't understand how a trojan does that - if, indeed, that's what is doing it.
Ray.