The issue appears to be resolved, but the specific action to achieve this is unclear.
Between asking the question and awaiting response, a number of Windows updates had been applied to my machine, and so having subsequently carried out a simple un-install and re-install, it's hard to say if it was the re-install, the Windows updates, or a combination of the two. To further fog the issue, I'm pretty sure my AV software (ESET) would have updated during that period, also.
All I can tell you is it's now working.
I'm sorry I couldn't give more specific advice.
FYI: I've since installed IE9, and it works fine. I've also tested with Google's Chrome and, again, that works OK too.