Thanks for your help. I haven't tried it on the desktop yet, but I believe I found the problem
My wife's monitor was going out on her HP/M$XP, so she hooked up my desktop monitor (since I'm using the laptop) and used it. After the first shutdown, it started doing the same thing as it did with my Linux - took a long time to show the login page, and after a couple of shutdowns, it refused to come on at all! All this time, I guess it has been the monitor going out, not a config problem.
I've got a spare monitor out in the shed, so if it still works, I'll hook it up in the next few days and do those fixes, and get back on the desktop!
Then I'll know for sure if it's the monitor or not! Right now, I'm working on an '/etc/hosts' file that's about 4000 pages long, to get rid of those pesky pop-ups and banner ads!