In case anyone is interested, I have been able to see the AdaIC site through
both Freeserve and [now] Tesco in the UK, but not through my 'default' ISP of
Demon. I have been corresponding with Demon via email, and have had 3
suggestions:

1) Try it again! Very useful - NOT - I pointed out that I have been trying it
again for a number of months with no success.

2) Check that I am not using a proxy - I pointed out I had problems with their
proxy when I first tried it around 5 years ago, and I've never used it since!

3) Let them know the results of 'tracert www.adaic.org' from the DOS command
line. (A worthwhile suggestion!) I have passed on the results and I am awaiting
a reply.

Through Demon, tracert managed to go for 12 hops or so to one of
sprintlink.net's devices then started to time out. This may be related to the
problem, but I also tried the same thing with (basically) the same result
through both Tesco and Freeserve. The subtle difference is that while the
requests were timing out, I was still able to load the AdaIC pages through Tesco
and Freeserve (but not Demon)!

I'd be interested to hear if anyone else on the list uses Demon as their ISP
and, if so, whether they can see the AdaIC site through them.

Thanks
John

PS if this is too off-topic for the list, please let me know.