Qt Creator runs slowly under Windows 7 64-bit when Workstation (widows service) is running

After installing QtSDK 1.1.1.3 I found I could not run Qt Creator. The program would show as a running process but there would be no user interface at all, even after leaving it for 15 mins or so.

No problem if I booted Windows in safe mode. After turning off each service in turn and rebooting I narrowed it down to the 'Workstation' or lanmanWorkstation service.

If I turn the service off then Qt Creator runs fine, it the service is running then it doesn't.
When it is running, the service restarts itself, and after this, if I select Projects and switch between say Build settings and Run settings, then Qt Creator says 'Not Responding' for ages. As soon as I stop the 'Workstation' service then Qt Creator becomes responsive again.

Whilst the service is topped then switching between Build & Run settings is immediate. As soon as the service is running Creator says "Not Responding".

I had similar behaviour with Qt Creator 2.1.0 sometimes switching between Build & Run settings but there was no problem in starting Qt Creator so I did not work out the link with the Workstation service.

I have not seen any other report of this behaviour but maybe it is restricted to 64-bit windows 7?

Maybe there is some issue with the different use of forwards and backwards backslash between Qt and Windows such that windows thinks Qt is requesting a remote computer or file share which takes forever to time out before signalling 'not found'?