Thanks Chaps,
The OS is XP with SP 2.
I have installed and unistalled every possible combination of the full set of Quartus
tools many times, but the best I have arrived at is the current unhappy state
of affairs using V6 of IDE.
Only today - totally out of blue and without having tried any new instalations etc - IDE refused to download my build complaining about jdi files. I don't know what jdi files
are but they may have something to do with the flash programmer - which I am not using.
I had to once again uninstall the IDE, and then reinstall it again. It is now
working, apart from my problem from the original post.
I have been using Nios IDE for a over two years now and whilst it is great for getting
test software up and running, I have a lot of issues with it. In particular the constant,
varied and unrecoverable crashes.
I am told the Xilinx stuff is even worse, so I suppose I am stuck with it.