The message that I received is : Cannot connect. Not very informative, is it?

I get approximately the same response from IE on the same machine or a different machine. Its the same with FF on both machines.
Yes, I've already cleared the cache, cookies, etc. on both but it had no effect. And yes, I'm using https & port 7071 - and this is only on the LAN, not WAN so it doesn't involve firewalls or port blocking. As I mentioned before, everything has been working fine until yesterday morning. FF dying was only an after effect and probably no way involved with the admin console disappearing as I get the same response on different machines.
As I mentioned, I did look through the log files, but I didn't see anything out of the ordinary as I compared entries from (now) 48 hours ago to 24 hours ago. Is there one particular log file I should inspect more closely? I mean, there are only over a dozen there and I have a lot of things on my plate so I can't be spending the entire day reading log files...
Again, I would think that there would be something obvious in one of the logs - just which one would have it? And the link that you sent me pertains to 4.5.x installs - I'm running 5.0.8. Any difference in log files/locations/names between the two major versions?
Thanks for the suggestions...
m