Thanks Wayne. Luckily we have very good relations with IT on this, and IT has significant MAS experience. It was rights and a bit more. In this case IT had previously (and correctly) installed client on TS. This is a relative new customer for us, and we hadn't yet had to do any installation work.
Then last evening Chuck uninstalled and reinstalled the client to fix a PDF dll issue. It ran fine. Of course our login has Administrator rights, so we didn't see the issue that users saw first thing in the morning.
It would have been ok except that we'd reinstalled the client to the standard c:\ location, not the odd place that IT had originally used. That also created a wave of issues because of (clever) way IT had set up shortcuts.
I think the lesson is that when you first re-install in and environment you did not set up, especially on TS, at the very least log back in as NON-Administrator to check the job.