Ticked too soon I'm afraid. Once again my d-link 604T is showing 4 static and 1 flashing green but there is no internet coming through. Again I cannot access the setup on 192.168.1.1. All I get is timed out or page not found etc. Tried unplugging for between 5 mins and 1 hour after which it all seems to come on-line, network icon at the bottom right corner sometimes shows good and sometimes ltd/no connectivity. Either way there is no internet pages and no setup access.
Folks we appear to have cracked it. Thanks to all who took the time and effort. While it may prove useful to others to record the steps taken to rectify the problem, I have to say that when PCA forum went down this afternoon I decided to cut my losses and start from scratch. I removed all hardware and software from both machines and started again. I've no idea why the admin page disappeared in the first place but after googling the problem it seems it is by no means unique. Well all thats left to do is wirelessly connect the old hack that is in the loft. All set everyone?
Yep, after 4 hours trouble free surfing, it's dropped out again. Basically it works fine and then for no apparent reason you click on a page and that's it. No more pages 'til you power down/up. It's also at this stage that I can't access the admin pages.