Hello Dawood,
As ever you were on the right track with this. I followed your advice and found that after I had applied changes to Host things all began to kick back into place - the IP addresses reappeared as if by magic... I still don't quite understand how/where Contact Centre configures these - presumably there's something within the programme that binds the IPs - they don't show on the NIC IPv4 tab but they are there when I run ipconfig /all.
Just for information, we use a single Active Directory user to run everything (except the SQL Server Agent service which has its own service account) - and I tend to log on to the application server with that user (which is Administrator at Windows level and is also Sys Admin on the SQL database server too (separate box to the app server)) and launch IA from there.
I've had various problems with this development server that I won't go into here but I have learnt a lot in troubleshooting them. Every time I think I understand how Contact Centre works, I learn something that makes me realise that I don't :-| It is such a complex product requiring a lot of end-user configuration, much of which I feel ought to be written into the programme and happen automatically. I completely missed the fact that there are differences between Apply Changes to Local System and Apply Changes to Host so thank you for your help once again.
Best wishes,
Adele