So I just got in and put away clean laundry and stuff and then sat down to try and Sort Out the PC.
The latest problem is that it's been asking to start in Safe Mode on startup, except the keyboard is a USB device and hence won't work until Windows loads, so I have no choice but to start in Normal Mode anyway. On the first time today I restarted it and then it was fine.
Then I did a System Restore to Saturday night (the latest time it would let me go back) which seemed to stop the bootup problems. Except then Internet Explorer wouldn't work properly and wouldn't find any pages. Also, the PCI USB thingy still wasn't detected.
I turned it off, turned it on again. The scanner made friendly noises at me to tell the computer it was there. Checked Device Manager. No exclamation marks next to the USB items in there. Internet works. All fine?
Apparently not. Scanner won't work. USB still not detecting anything. I suspected initially that my old camera connecting cable (which I pretty much use for everything) was just broken after too much use and being run over by the chair (*ahem*) but given that the scanner has its own cable and still won't work, despite happy hello noises, quite frankly I am now stumped.
Again: is it too much to ask for that things just WORK?