I mentioned a few posts back that, for some reason, my netbook had given up recognising the usb modem. I initially thought I had burnt out my modem (or whatever it is that happens to usb sticks when you don't go through the "safe to remove" procedure). But no, the modem worked in another computer.
After a little googling, I tried tweaking the port settings and so on, but to no avail.
Fortunately I was able to locate a restore point that turned out to pre-date my "clean-up", and yes, the software for the overseas modem was restored. But far more importantly, my netbook again recognised my usb modem! Apparently the software for the overseas modem had in some way affected the setup for my Australian modem which wasn't reversed when I deleted it.
I remain convinced that the underlying issue was the port settings, so I can't understand why my tweaking wasn't successful. However, on the principle that "if it ain't broke, don't fix it", I intend to leave things alone. But for once I knowledge that I owe a little gratitude to Mr Gates for giving us restore points.