BI4.1 SP2 IDT : Edit Join dialog OK button fails

Our system was recently upgraded from BI4.0 SP6 to BI4.1 SP2.

Problem : Information Design Tool (IDT) : Edit Join dialog : OK button click not being serviced.

To replicate on Windows (x64/x86).

1. open IDT
2. open a data foundation layer.
3. click on any Join to open the Edit Join dialog
4. click validate                      - works OK
5. click Detect Cardinality       - works OK
6. click OK                            - nothing appears to happen. ie. you can't tell if the underlying metadata has been saved BUT that is irrelevant because the Edit Join dialog has not been dismissed. The only way to exit is to click the Cancel button.

This has left me without the ability to modify universes where JOIN details require modification AND/OR new join's have to be added.

I have replicated this issue for both Existing and New data foundation layers.

Thinking that something else installed on my main (64-bit) desktop PC must be interfering somehow I have even wiped a laptop and re-installed OS and application from scratch.

1.      Window 7 (32-bit)
2.      BI4.1 SP2 Client Tools (Installation not upgrade)
3.      Microsoft SQL Server 2012 Native Client (32-bit)

     .... and the problem is still there.

Our vendor has been made aware and has seen this behaviour via remote connection but has so far been unable to replicate with their environment.

Anyone else experiencing this ? Any ideas ?

Regards

Scott